I might not have been clear about the carbon button; I actually replaced the broken one, so all was well with that part of things. But yes, I can see how it would be wise to keep one on hand for parts!
Christy and Mike, the foot controller has been futzed-with and tweaked, and I believe the sweet spot has been found.
Also I had a Smart Person check out the re-wiring and I was given an A+ for my job. ;-) Hooray, no shocks and fires here! I will run the machine and hope the snap crackle pop is indeed simply the moisture in the disks.
So, tomorrow I will put the motor back on again (it was taken off for inspection) and carefully adjust the belt. Perhaps it was too tight, causing buzzing resistance? It is a brand new V-belt, so that should be good. But I guess I have to find just the right spot for motor height.
I will also check the timing. I -think- it was okay, but I will give it a really good look in the light of day.
BY THE WAY.... the place where you drop the bobbin into (bobbin race?); should it move left to right a bit on its own, and when running machine with no bobbin or thread? I noticed this happening, and wondered if perhaps something is out of adjustment there?
Thank you again, everyone. I will be so happy when these final tweaks are done!