Hello, all, New member here. I thought about starting a new thread, but decided to tack onto this existing thread to make things easier for searchers in the future. I'm considering driving several hours to look at a Pfaff 138 here https://richmond.craigslist.org/art/d/sewing-machine-industrial/6770955579.html Spoke to the seller, and he said the brass plates on the machine read "138-6/21-BS" and "139936." In my research, I found that Pfaff 138s come in several variants. I guess the "A" variant is for lighter fabrics and the "B" is for medium weight fabrics. Question: Would the "B" at the end of the model number on the brass plate ("138-6/21-BS") indicate that this is a "B" version? What is the difference, physically, between the "A" and "B" versions? Question: Would I be able to use heavier needles on this machine? I got the feeling that one could use needles up to about size 120 or so on the Pfaff 138, but the manual suggests that 100/16 would be max on the 138 "B" variant. Question: Could I change the needle type used on this machine, possibly by changing or modifying the needle bar? The seller said it takes 438kk needles (and one website says this is equivalent to 265KK), but I see that these needles aren't very common (or cheap). If possible, I would like to switch to the common 15x1 system used on home machines like my Pfaff 130. (I was surprised that not all 138s use 15x1 needles, considering that the 138 and 130 share the same hook, bobbin case and bobbin, etc...) Machine would be used for boat canvas, light upholstery, garment construction, garment alterations and repairs, etc. I've been fairly happy with my Pfaff 130 for these purposes, but would like a bit more power, as well as the knee presser lifter and foot-pedal reverse (I'm actually thinking of trying to rig a knee lifter on my 130...I can tig weld and fabricate...) (Also considering trying to find a Pfaff 545 for the heavier jobs –such as heavier canvas, webbing and truck/boat upholstery – and selling off my Singer 201-3, whose capabilities would be covered by the Pfaff 130 or 138 ... I don't have room for a whole bunch of sewing machines. If I could keep it to two – maybe a Pfaff 138 and a Pfaff 545 – that would be ideal...) One last question: I always heard that the Pfaff 130 contained no plastic parts at all, but I discovered that there is a white plastic (nylon?) gear in the machine (I think it has something to do with the zig zag) and I have read that the hook is driven by some kind of "composite plastic" gear ... does anyone know whether the Pfaff 138 has any plastic parts prone to breakage? Thank you in advance for any help. Wellington.