Looking at the contacts, they don't look like they have a corrosion problem, but maybe - gotta be something.

Just before checking for responses, I did try the pencil eraser. I used to play with slot cars too! It may be awhile before I'll know if it worked. I've made rides of 25 miles with no noticeable problem. I can tell because I always get very consistent readings of 12.52 miles one way. It might sometimes say 12.51, but nothing else unless it is acting up.

If the problem isn't solved, I guess I'll looking into the WD40 approach.

Thanks to both of you.

Bob