[BenI]

Mine started jumping before it totally went dead-the problem was at the gauge end of the cable. There is a crimped-on fitting that adapts the round (essentially a long spring) cable end to a square pin that drives the speedo. This fitting had come loose from the cable. I ended up replacing the cable-kind of a pain in the ass but not too bad, but I think JB Weld couldve fixed it too. I also had the elbow drive at the tranny go on another 914, but this just made the speedo die, no jumping around. I would pull the gauge out and play with it and the cable end first.