Grind or sand off the the tips of the teeth,they really aren't needed on a walking foot needle when sewing leather BUT it will create less drag if the feed dogs lift the leather off the needle plate so you might want to put the feed dogs to the original height.
With the way the servo & speed reducer work & how lightweight they are compared to this setup would be overkill on a sewing machine(esp with all the extra parts on it).BTW we had a variable speed like that on our old Massey Harris self-propelled combine that I used to run on our farm & it would eat a belt every couple of yrs,as long as your were moving you could slide the lever up & down pretty easy though.
I've never done it they way jimi says.I've always just used a small punch or nail & hammer it out from the bottom of the post(there's a hole in the casting for this) it's a pressed in fit & then you have to tap it back in to re-insatl.
This machine is the same as the Consew P1206 we've been selling & we haven't had issues like this with it.You have some good advice already & it sounds like it needs some oil on all the walking foot parts underneath the cover & you possibly could have the tension too loose so you might have to increase it a little to make it go down.And after you use it for a month or so you can loosen the pressure foot tension once it gets broken in.
Sometimes the needlebar thread guide gets a groove worn in it from the thread & will cause this,you might look @ the hole on the inside foot(on the bottom side) it can also get grooved from the thread.We stock edge guide feet & a drop down guide too.
No,it won't because you'll still have the same amount of pressure.Your marking with this type of leather would be less with a lighter pressure foot spring.I also know a lot of people just rub the marks out w/a spoon or bone.
It's a step in the right direction BUT the pulley only has on set screw & if you start sewing anything very thick in time it won't hold,that's why they put 2-screws in the original pulley that line up with the grooves in the shaft.
Sailrite is high priced on everything they sell,we sell the for $4.00 a pk.