kgg

I think they are using the " Gunze Count standard " where the larger the number the thinner the thread for a given number of ply. Those sizes would be typically seen at your local fabric store in those small domestic size spools. The number is referring to the weight of the thread but not the number of cords (piles) that make up the thread. Where a #30 2 ply isn't the same size as #30 3 ply but is labeled as #30 weight. Confusing??? From the needle size the machine should be able to handle correctly thread up to V69 (T70, Tkt 40). kgg

Since both suppliers are close I would check and see what additional parts are supplied with the machines like 1) Deburring tool to remove burrs off the inside of the knife 2) Metal roller to get rid of the material that builds up on the outside of the grinding / sharpening stone, I think Consew calls theirs something like Super Radar roller. If both are equally equipped then it is down to whoever gives the best price. kgg

Thread information can really send you down a never ending rabbit hole. Particularly when you compare single to two or three core. kgg

Depending on what they are making and if they are using a single or double needle machine they can assume they are using for single-needle sewing machine the Z-Twist (Left Twist) or they could actually twist the end of the tread thread and see which way it starts to unravel. Besides the size, type, weight and yards or meters of thread information on the label I think the most important information is missing. How many twists are there on that spool of thread per yard or meter not how many yards are on the spool. With more twists per yard you get a smoother stronger thread which costs more to make and buy but should give you less thread related problems. kgg

A short video or a couple of photo's would also help to narrow your problem down. I am going to assume the feet you installed are similar too: ( https://www.amazon.ca/dp/B07DLM7LMY/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=b31bc0359e2199439acb987303abc3b4&hsa_cr_id=6896265850101&pd_rd_plhdr=t&pd_rd_r=5e2bf340-8f69-4fd7-beb4-add8a7c89d2d&pd_rd_w=FiTjG&pd_rd_wg=uH38g&ref_=sbx_be_s_sparkle_mcd_asin_2_img ) A couple of good video's for your machine which may answer some of your questions would be: Pressor foot install: ( www.youtube.com/watch?v=1o-WTYIKpvw ) Pressor foot tension: ( www.youtube.com/watch?v=7BdkLXoqu1Y&list=PLR4xEBIfN8Fyf6cjerMhAvwqClVzx8Zbc ) Also as the material being sewn becomes thicker you would need to reduce the tension on the pressor feet. The needle you are using (110/18) is incorrect for V92 you need to change to at least a #19 or 20 and in thick/tough materials a # 21 or 22. Are you using a leather needle (135x16 ) or a fabric needle (135x17)? kgg

Personally I hate most pastie type greases as most like lithium white grease are dirt magnets and you typically see the mess like what you have shown in your photo. Normally I choose to oil regularly with a synthetic oil concoction on my sewing machines but on those odd occasions that I have to use a grease I still prefer to use a light coating of synthetic gear grease. I find the synthetic's give a smoother operation to gears and bearings. kgg

Option suggestions: 1. Why not make your own belt. I just purchased some 10 meters (32.8 ft) of 6mm diameter Rough Surface Green Polyurethane off Amazon.ca for $28.79 CA ( https://www.amazon.ca/gp/product/B07W5L7NPV/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&th=1 ) plus tax to make a new drive belt. This will be the main drive belt from a repurposed sewing machine motor a Rex 550 watt servo motor for my new to me Atlas lathe. 2. Buy couple off Amazon they are cheap, two for $14.99 CA ( https://www.amazon.ca/CKPSMS-White-Industrial-Sewing-Machine/dp/B08CXZBCXZ/ref=sr_1_2_sspa?crid=3NE9LYGBI4UIM&keywords=56%2Binch%2Bsewing%2Bmachine%2Bdrive%2Bbelt&qid=1642740205&sprefix=56%2Binch%2Bsewing%2Bmachine%2Bdrive%2Bbelt%2Caps%2C115&sr=8-2-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFTSjEzOTRBRFBOMUomZW5jcnlwdGVkSWQ9QTA5MDI5NjkzSFBFUElNN1lYNTdNJmVuY3J5cHRlZEFkSWQ9QTA2NDE5ODgzNkpLQTJETjVNS0hYJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1 ) kgg

Some servo motors do have a reverse rotation switch on the back side. I have a Rex 550 watt servo with this reverse rotation direction switch while my other servo's don't have that feature. kgg

Looking at the manual for the SC-9 and the CP-130 (my search: juki with cp-130 controller wiring and found a good manual called "Control panel CP-130 INSTRUCTION MANUAL - Amazon S3" at s3.amazonaws.com.) and yes it is an overvotage error. What I did notice is there are three wiring diagrams. One for single phase 100-120 VAC, One for single phase 200 - 240 VAC and One for 3-phase 200-240 VAC. With the E11 are you sure it isn't single phase 200 - 240 VAC not 3-phase 200-240 VAC? kgg

I am not familiar with that machine but for those dollars I would be concerned with the lack of dealer support and down the road for repairs and access to replacement parts. Maybe better off getting a good used machine that has dealer support. kgg

What is the model numbers of the Juki's??? as the manual for those models may help. kgg

I good chart can be found at (https://www.tolindsewmach.com/thread-chart.html) also you should normally use the same size thread on the top as you use in the bobbin. The strength of the seam will be limited to the strength of the smallest thread size. Sometimes this is done for the look that a larger top thread gives or sometimes you can fool a machine into using a larger top thread then the machine is rated for by using the smaller machine rated bobbin thread. kgg

What may help also is if you check the ismacs.net site for Singer 99k or even the Singer 66k manual ( https://ismacs.net/singer_sewing_machine_company/manuals/singer-sewing-machine-manuals.html ) kgg

Remove the leather string at the end of the handle and install a metal "O" ring and would make a great protective key chain. Is that teeth marks in the jack? kgg

Looks like the spring that keeps the bobbin ejector button ( the little round cross hatched button ) in it's normal up position is either broken or has become displaced. Maybe the red fuzzy stuff got caught and someone dislodged it taking trying to remove the red stuff. kgg

All very nice inexpensive useful designs. Great repurposing. kgg

Yes the selection of machines can be confusing, at times overwhelming with machines having similar specs and trying to figure out what some of the clone machines are closely related to. If I were now looking for one primary machine that would cover most items I would try and figure out what items would fall in the 90 percent bracket and buy either a really good used or new brand name machine to cover those items. If those items are done better on a flatbed like wallets then buy a Juki DNU-1541S (new~$1800US used ???). If you are doing 50 / 50 then get a cylinder arm machine and with a table top attachment like a Juki LS-1341(~$4000US) or and older Juki LS-341. Buy Once Cry Once kgg

These can easily be converted to 135x16 system by simply adjusting the needle bar up by about 5mm from the original position. kgg

Great news. kgg

Yes, their are no more true PFAFF's, Dürkopp Adler's or Maschinen GmbH ( Mauser ). They have been all acquired by the Chinese company called SGSB GROUP CO. when the ShangGong Co., Ltd. merged with Shanghai SMPIC Co., Ltd. back in 2005. They acquired PFAFF in 2005 and in 2013 acquired Dürkopp Adler and Maschinen GmbH ( Mauser ). The question for me is are those old respected brand names now just overpriced China clone's with an acquired brand name badge????? kgg

Try a led magnetic light from Amazon.com that should brighten things up. You can get two for $15.99 US ( https://www.amazon.com/AUTIDEFY-Lighting-Multifunctional-Gooseneck-Workbench/dp/B09K7F45Z4/ref=sr_1_12?crid=Y59GJ6BO0Y8R&keywords=led+sewing+machine+light+flexible+work+light&qid=1642258315&sprefix=led+sewing+machine+light+flexible+work+light%2Caps%2C50&sr=8-12 ). kgg

Yes the thread size 69 and 92 refer V69 (Tex 70, Tkt 40) and V92 (Tex 90, Tkt 30. A good reference table for thread sizes / strenght and needles sizing can be found at ( https://www.tolindsewmach.com/thread-chart.html ). kgg

Without the thread threaded through what I notice: 1. The thread guide is not original as their should be two separate thread guides that mount in the holes just above the thread tensioners. 2. Are you following the Singer Manual for timing? If you don't have the manual you can get one here ( https://www.manualslib.com/manual/364320/Singer-112w139.html#manual ) 3. To thread the needle you need to use the thread controller discs closest to you and the thread needs to go throw the hole in the take-up arm closest to you. 4. The spring in the thread controller seems to be at roughly the 7 pm mark and should probably be adjust to the 9 pm position. 5. To do the needle to hook timing slide the cover plate off so you can see the hooks placement in relation to the needle rather then trying to see it from the underside. A photo of how you are threading from the needle would also be helpful. What system of needles not the size of needle are you are using as this can make a perfectly timed machine to not be able to sew. kgg

Excellent work. kgg

Another option would be the 3/4 version the Singer 99. kgg