The speedometer on my 85 245GL has a mind of its own (I kid you not). The odometer, trip odometer, and every other instrument in the cluster has never stopped working. However, the needle on the speedometer has. It has always shaked between 0-30mph, soon after reaching a stable state. I don't know how this is related. Regarldess, the actual problem is that it periodically stops functioning. It does this about once every two weeks or so, and then begins to work spontaneously as if nothing happened. The period where it doesn't work is never more than 15 minutes. Could this be a loose wire, or gear? Is it something I should attempt to repair on my own? Any words of wisdom would be much appreciated.