CB750F 1980 Tachometer Stuck at 2 Grand

[hueylouie]

I have a 1980 CB750f.
The tachometer is stuck at 2 grand when the bike is off and running no matter the engine speed.
I've disconnected the cable from the bottom of the tach and while the engine is running I can see a piece of cable about 1/2" long rotating inside of the cable. When I bought the bike the guy who sold it to me showed me this and basically said it was an issue with the gauge.
I don't really know how these gauges work but I'd like to try and repair it if can.
If I can't fix it.
Would any of you know how I should go about purchasing an aftermarket gauge assembly? Or what specs to look for when purchasing one.

 

[brettp]

Put a light into the tach cable housing at the engine to make sure that is turning with the engine running. If it is, then the tach gauge is the problem. You can find them on ebay.com.

 

[Connella08]

if you disconnected the drive cable from the tach itself and it does not drop to zero, then it sounds like the problem is within the tach. try disconnecting the cable from the engine and spin the cable by hand backwards to see if you can get the needle to move closer to zero.