Fixedgearhead

If I want electric I have that on a different machine.[/quote]
When I did my conversion, I talked to the owner of the Bernina Dealership that provided the parts, and he said they made the Brass, and now steel hand wheels, because there needs to be a bit of momentum to sustain the continuation of the power just like a flywheel in a car. But, if they are leaving the motor and electrics in place, they take off the internal drive belt from the motor to the shaft, as it adds drag and is not necessary. If you want to switch from electric to treadle, then you could just release the tension on the drive belt motor so as that it does not add drag when using it as a treadle. As to slippage. If you are doing a restoration of the Singer, and just want to leave it for display, then using the leather belt is fine. If you expect to use it for real sewing, then get a modern Poly belt and never have to worry about slippage or adjustment again. I have had my modern belt on the treadle conversion and have never adjusted it for stretch for 3 years of heavy, and I do mean "Heavy sewing. I have sewn for 8 hrs a day on some projects, and done some seriously horrible sewing through some things that resemble plywood, in their thickness. and it has never slipped a bit.That machine is really the only machine I use for sewing. I love it so much and it suits my style of sewing. I have sold off A Bernina 430 modern machine, A janome 1600, Professional, and I gave a friend a regular Janome (I don't remember the number) because it did automatic button holes and the gal I gave it to didn't have one and was complaining about the button holes she got from her machine. I sew Clothes, Quilts, Craft stuff, Curtains, You name it. This treadle does it all. Albeit A bit more slowly. I have thought about purchasing a Commercial heavy duty machine for those projects that are heavy duty sewing, but this machine does them without any problem. I have adjusted the timing one time, but it was still within the range of acceptable, but I had been abusing it and felt guilty and wanted it to be back to normal if it could be. A great project that has proven to be one of the best things I have ever done to a sewing machine.
John