1969 Speed Warning Speedometer Question

[Todd68Chevy]

I bought this instrument cluster at an auction and do not know much about the speed warning option. The speed warning needle turns fine and gets tight down by 20 mph so I think it is all working correctly but the speedometer needle is not. First of all it is sitting in the middle. It is not frozen. The part where the cable attaches still spins both ways but when it is spun forward the needle seems to move as fast as the back is being spun and then went it gets clear around to pegged the needle stops and the when I stop spinning it the needle comes back around and stops randomly in the middle. If it is spun backwards the needle does go down to zero and stays there until it is spun forward again. I know the speedometer are specific for these clusters and if it is junk that that makes a big difference in this clusters value. I really do not want to disassemble this cluster but I have someone interested in it and would like to tell them what this might be so they know what they are buying. So it is hard to explain what it does but hopfully you can understand what I am saying. Thanks for your help.

**If this is in the wrong area please move it.**