My apologies if this has been answered before, but my attempts at searching didn't turn up what I was looking for.

I have a 1986 Sunrader, automatic, with the shifter on the column. Sunrader is built on a Toyota Pickup with a 22RE engine. The gear indicator on the column stopped working. Like I can have it in Drive and the orange dot shows Reverse. Or sometimes it shows nothing at all. I can get it into whatever gear I want easily enough by counting the clicks, and the truck knows when it is in reverse and such (like the reverse lights come on when they should), but that little indicator just doesn't work.

Are there some common troubleshooting steps I should try to figure out what's up with it? Or is there a way to get it lined back up?