And then once you've cleaned out the dust and grime, you should probably apply some sort of contact cleaner or lubricant to each of the controls (except maybe the width coil) to help prevent the problem(s) from reoccurring.

Also, if you haven't yet, you should recap it. That will spare you a lot of troubleshooting grief later on (and, given the age of those things, it's inevitable that something will fail.)

I'm glad it's working for now, though.

c