Jeff, the following is the method for 35-type dials.
Take a clean piece of good quality bond paper, and make some strips about 1/4 inch wide.
Take the plastic dust guard off the dial, and then look at the edge of the dial, and find the 7 sets of make contacts. There is a set of contacts for each of the 7 tones that create the matrix of 12 digits.
Insert a piece of paper into a set of contacts, then gently pull the paper through the contact set while depressing a button that activates that set.
Repeat for all the sets. It's a wiping action that tries to overcome the friction of the contact pair. It takes a little practice.
Then, look at the "common switch" which is a series of make and break contacts on the rear of the dial. You will notice that whenever you press ANY dial button, the common switch operates.
Use the same method as above for the normally-open sets of contacts. Then, for the normally-closed contacts, press and hold a dial button, insert the paper slip, and then release the dial button, while doing the wiping thing. Repeat for all the common switch contacts.
In your case, the problem is one or possibly two of the sets around the perimeter of the dial, but it makes sense to do all of them, and the common switch, while you're at it.
