J Miller

Looks like the stitch length instructions are dead on.

Many motors get over oiled and or filled with dust, lint and even pet fur. "Usually" they will clean themselves out with use. However sometimes you have to clean them. A Sewing machine guy I know squirts lighter fluid in them at the brush area then runs them at max speed for a few minutes. I've not used lighter fluid but I have used denatured alcohol and break cleaner. If that doesn't work, then the motor will have to be disassembled and cleaned.

The foot controller should not smoke at all. That can be taken apart and cleaned if there are no broken parts or shorted wires. If it is a carbon pile controller there can also be broken carbon disks inside. This causes an overheat condition.

You would not believe the junk that will build up in foot controllers. Here's a pic of the build up of stuff I found in one:
[ATTACH=CONFIG]526202[/ATTACH]

Here's one with broken carbon disks:
[ATTACH=CONFIG]526203[/ATTACH]
"IF" you can find replacement disks controllers like this one can be cleaned and repaired. Mater of fact I did have some extras I got from another forum member and did repair this controller.
It's so much easier to replace them though.

Yes, the SEWMOR 606 will fit in a Singer cabinet. Almost all the machines sold use the Singer dimensions except the White made machines and many of the Kenmores.

Joe