Yesterday the speedometer on my 929 started acting up. It is good one minute and flat the next. The cruise control does not work nor does overdrive. The "HOLD" light flashes. It is almost as if a relay is operating intermittently. Any thoughts?

 

Could be your speedo cable is shot. And if the cruise is driven by it then an unstable cable will throw off the cruise sensor too.
You might just try lubricating the cable first and see if that works. Remove it from the back of the speedo and spray lots of lubricant into it.Then reattach and drive for a bit. If it does work, don't expect that it'll last forever that way.