As spring approaches, I'm realizing I need to get the speedometer working in #5316.

When I bought the car, it had no dust shield and a seized angle drive. I bought a new angle drive and dust shield from delorean.com, and that lasted a couple of years. Then the speedometer became intermittent, low-speed only, then nothing. I lubricated the cables. The lambda counter is still hooked up with the cable, with the wire disconnected by a previous owner. I've pulled it out and tested it, but it doesn't appear to be slipping. With everything hooked back up, I pulled the dust cap and tested the cable with fingers (turns freely) and a drill (reads highway speeds, easy). I suspected the dust cap was spinning against the wheel, but gluing it on with lock-tite didn't help (I got about half a mile out of that). So I pried it off, bought a new dust cap, and that fixed it for a couple of months before the problem came back.

I suspect that the square hole in the dust cap that accepts the speedometer cable is rounding out, and the only thing I can think to do for it is to fill it with JB Weld and try to mold it to the cable without effectively gluing it on. Before I go to those extremes, what else should I try? Is there a better dust cap on the market? Am I missing some other component to test?