1997 lesabre speedometer problem

The speedometer on my 1997 Buick Lesabre will not work for extended periods of time and then all of a sudden will start working but it jumps up to 100 miles an hour when I'm going 40 and then jumps all over the place. After doing this for a while it quits working again. Also, I cannot find the power steering reservoir! Any help is greatly appreciated.

Look by the firewall on the acc. drive belt, way down low, there is the PS fluid