A different style classic Singer foot controller
 

I've only run into the one type controller before. Usually when I open them up they look like the brown one. This is the brown controller that had an overheat issue and even though I cleaned it, re-wired it and it works it makes me nervous. I dug into my box of spare controllers and pulled out this black one. The guts inside are similar but not the exact. Is this an older model? or maybe a younger one?

Christy,

They're both the same type of controller. There are little carbon disks inside the large housings. The grey one on the right is "I think" the newer one.

The one on the left has been way too hot. I'd tear it down and clean the insides of carbon deposit and make sure the disks weren't broken or missing, then very carefully clean them too. They are very fragile.

ArcaicArcane has a dandy tutorial about those things here: { http://www.archaicarcane.com/singerattheraces/ }
And some more here: { http://www.archaicarcane.com/what-a-pile-of/ }.
The wiring on the brown one needs checked and probably replaced too.

If you haven't done these things already.

Joe

Thanks Joe! Yeah I already tore down the brown controller, cleaned everything including the disks and changed the wiring but I am still not sure I want to trust it.

Since I do have a spare available, I will attach a note to the "bad" one and probably save it for extra carbon disks if I need them. I feel safer going with the other controller.

I would trust it... on probation and assuming you've changed the cord - I think you said the original was too short after removing the corroded portions. Don't stick it in the knee lever mechanism but put it on the floor, sew in socks ad monitor for noise and heat. Sew slowly, that's the way you generate the most heat. I bet you'll find it's fine. The one for my 403 worked til (at least) the day I sold it more than a year later and I use that process to check / fix all of my pedals these days.