I started what was supposed to be a simple swap of 120 mph for the 85 mph speedometer in this car, a 1983 240 GLT turbo. These are mechanical speedos, r0,980. After the initial replacement and test drive, I find the speedo doesn't work. Everything else does in the instrument panel does. I thought I got a bad deal on Ebay for the replacement speedo. But, when I reinstalled the original, that doesn't work now either. So, I think both speedos are Ok and it is either the cable, that it was about to go and my fiddling insured it, or my technique for installing the cable. Is there a trick to getting the cable in properly? Seems straightforward enough; insert the cable to the back of the instrument panel and tighten down the locking nut. In my experience with most things that attach like this, the locking nut won't wont catch the threads unless the alignment is correct and allows the pieces to fit properly. I am now without a functional speedometer. If any replies come in soon enough, I can still try to fix today while there is daylight still left. Thanks for reading this.