Trip Computer Problem

I need some advice and or experience about my trip computer which is now normally just blank but occasionally it will show some gibberish. Does anyone know What is causing this and what can I do to fix it?

The early 1985 and earlier trip computers are susceptible to hanging caused usually by a low-battery condition - if the battery is at all weak, while cranking the engine the voltage will droop enough to mess up the computer, but not enough to give it a clean reset. You need to pull the fuse and put it right back - that'll reset the computer and clear the hang. Alternatively you can briefly disconnect the battery. If this keeps happening you may have a weak battery.

Simon Budd asked

Does the trip computer just slide out of the dash or does it have retaining clips somewhere?

It's retained by a spring clip on either side (L & R). It will pry out. Grab one end, get fingernails under bezel edge and rock/pull on it till that sides spring clip lets go. Then do the same on the other side. There are two molex style connectors to disconnect, and that's it. Once you replace the rivet with a screw, there is a tendency for the screw head to hang on the cutout, so a little more care will be required. Good luck!