James,
Yes, that appears to be what the problem is. I was thinking that there must be something other than the just the shaft making contact with the bushing so I took it apart again today. The problem was with the way the wiper makes contact with the brass bushing. Here is the underside of the wiper:
The place where I am pointing to is what makes contact with the bushing. Here is the bushing it makes contact with:
If there is too much play in the up and down movement of the shaft then the area that I am pointing to does not have a consistent and reliable contact with the bushing.
The wiper is crimped on:
What I plan on doing is (carefully) removing the wiper and putting a bend on the circular section that I was pointing to so it will stand up more and make a better contact with the brass bushing. It may be a day or two before I have time to do this. If anyone has a better idea please feel free to offer it up.
- Geoff