The early wind up clocks on standard 93's are pretty easy to fix.  The hardest part is removing the tiny brass mounting screws that hold them to the back of the dash.  The screws were usually smeared with a dab of glue to prevent them from falling out.  Remove the glue with a knife before trying to back out the screws.  Once you have the clock removed, spray electrical contact cleaner on the "works," followed by blowing out with compressed air.  The next step is to spray the works again with silicone spray.  Unless your clock is badly rusted, this should be enough to get things moving again.  Sometimes you have to flick the little wheel that spins back and forth with your finger a few times to get things going again.  

The 1960 through 1963 95/96 clocks are electric and also stop working from sitting idle too long. To open them up you have to remove the rear plastic cover.  You will notice a 1/4" diameter round metal circle on the back.  This is actually a screw that holds the back on.  Just grab it with a pair of needle nose pliers and turn counter-clockwise to remove.  Once the screw is out, the plastic back will slide off exposing the works.  Follow the cleaning procedures above but allow a little extra time for things to dry out before connecting the power.  

If cleaning doesn't do the trick, you might have a poor electrical connection somewhere.  The clock has a set of contacts inside that can be cleaned with emery board or fine sandpaper.  Also check the little brass contact that gets soldered to the top of a solenoid.  This can sometimes vibrate off.  If it has, just solder it back on.   I'm guessing that the vast majority of non-functional clocks can be repaired using these directions.  If your clock still doesn't work you can send it to one of the many clock repair people listed in Hemmings Motor News.

Bruce Turk, 2/01