[JP Noonan]

I had a '72 speedo that a PO left unhooked for countless years. When I re-attached it with a new cable it broke the cable because the grease inside the speedo had broken down and froze up the gears.

Take the speedo out and rotate the input thingy on the back of it with a small screw driver. There should be some resistance, like winding a watch, but it shouldn't feel like molassass. Even just rotating it by hand (twirl it between your fingers) you should be able to see the pointer move.

Disconnect the cable at the angle drive and rotate the cable (counter clockwise I beleive) with a drill at low RPM while someone watches the speedo. Go slow at first until you figure out which way is the correct direction. If it dosen't work and it is a 70-74 the cable is most likely shot. If it is a 75-76 there are two cables, one goes from the trans into a counter box (every 10,000 miles it lights up the "EGR" light on the dash) under the pass foot board, and one from the box into the gauge. If it does work the angle drive is probably toast. Remove the angle drive and rotate one end and see if the other one rotates.

I posted a few months back on how to convert to a new VDO "Vision" electric speedo. Maybe look into doing that?