90 buick lesabre speedometer problems.

For a couple of years dads buick speedometer would fluctuate or not work
at all. I just inherited his car and want to restore it (only 65K for miles). I turn
key without starting engine and speedometer goes to 45, stays there when
running. Cruise light goes on but cruise does not work. Dash board lights
don't go on although I can use switch to turn on interior light, and all idiot
lights work. I'll accept direct email for answers at dvictoria320@comcast.net
or thru this forum.  Thank you for help..