Sewing Machine Problem

We have a problem. Our problem is this:

This is a Singer Model 347, built in the sixties (it looks like) and it seems to be a sewing machine that can do what we need. However, it has exactly three speeds:

1. Off
2. ON!
3. Manual

The ON! is the problem, in the sense that there are times when you don’t want the sewing machine to go full blast through your project; sometimes delicacy and slowness is required.

Here is the root of the problem:

You can see in the image, to the right, the switch which is actuated by the foot pedal itself. This pulls the contacts from the left to the right, bridging the gap and completing the circuit. Here’s a pic with some annotations.

I do not see how, if no parts are missing, this switch was ever intended as a graduated speed foot switch for a sewing machine. There are only two cables. I’m assuming one is hot and one is return and therefore this translates to an on, off switch writ large. Where the gap is bridged and the copper contacts touch, there’s no room for “play” in the touching or not of the contacts. I screwed around with this by hand and while, yes, there was a tiny bit of speed control just at the interface of contact, it was so minuscule and twitchy that I don’t see how it would be useful to a sewing task.

Possibilities:

• I have no idea what I’m talking about with respect to circuits. Quite possible true
• There’s a part missing which does the speed control. Doesn’t seem likely, there’s no obvious room for something that isn’t there anymore
• The foot switch is just so old and used that the functionality I’m looking for has given up the ghost. Well, yes, but then I should be able to fix it. This seems a really simple device

Any advice is appreciated.