I've been fighting intermittant problem's w/ my wife's 92 960 speedometer for a while now and everytime I think I have the problem licked, it pops up again. I'm hoping someone here can point me in the right direction. Here's the story:

A few months ago the speedo quit registering speed and, of course, the tranny was going crazy- I assume because it wasn't getting the correct signals. I took the speedo out to check connections, etc. but nothing looked amiss. Checked into getting the speedo repaired (about $200 or more) and decided to try a used one. The guy I bought the used one from assured me it was good. Put it in and the speed didn't register, but the odometer worked and the tranny seemed to be getting the correct signals and shifted fine. A few days later the speed started registering-hmmm? I left the cluster surround piece out after putting in the used one because it is such a pain to put in and I wanted to be sure everything was working before I went to the trouble to button everything back up. Well, of course, after I buttoned everything back up, the speedo quit working completely (flashing arrow, tranny jumping, etc.). So now, I'm wondering if maybe the circuit board is bad, or I have a wiring problem or if this used speedo is flakey. I don't know whether to try another used cluster or get the original speedo fixed and use my cluster. Anyone have any ideas? Thanks.