Can't get a break

Speedometer in my Dart is wack out , does the bumping thing. Was going to get a GPS but thought no I'd like a functioning speedo. Took the cheap way out and won (or Lost depending on how you look at it) a used cluster
guy said He wasn't sure about the speedometer , well it dosen't and now I'm back to square one. I'm thinking about sending mine in and having it fixed. Theres a place fairly close that will fix them reasonably. The cluster I got my be going up for sale guages work.