silly speedo question

[fireguyfire]

The speedo cable on my 68 was pooched and my new one arrived today. I have the dash cluster pulled forward so I thought I'd test it and make sure the speedo is okay before hooking up the new cable. I took the end of the old cable that is square and connects to the speedo outlet.
If I try to turn the speedo by hand by spinning this 6" piece of the old cable, I only get about 1/2 a revolution of spin in either direction (clockwise and counter clockwise) before it hits a positive stop with a bit of a "clunk".
So basically I can only spin the cable back and forth through half a revolution.
Does this mean my speedo is pooched, or is there a way to fix this problem?
Anybody had a similar issue before?

[new2muscle]

 That speedo has had it. If ya have a speedo shop locally, take it there, otherwise, a replacement is your other option.

I have been lucky only once in finding dirt in the mechanism and cleaning it. They are rather delicate things.

  Good luck- Steve