[C320-list] Tachometer only works at startup

[Clay Carter]

I have a 1994 Perkins M30.  Tach works for about 2 seconds only at engine startup and then falls to 0.  With engine running the hour meter which is located in the tachometer continues working. Thoughts on what the issue might be?  The tach itself?  Sender?  (Is there a sender for the tach?)
  
Thanks for your input.

Clay Carter
#225 We’ll Sea
Alamitos Bay, CA