Chafer 418 sp sprayer engine issue

[jjm]

Looking for a bit of advice please...
I have a chafer 418 self propelled sprayer that suddenly loses its pre set engine revs when it is working. Then today the revs were set to just above minimum to reverse it out of a shed when it stalled??.
You pre set the revs on a push button and be going along fine spraying when suddenly the revs drop to idle speed and you then have to press the button again to bring them back to the required speed. It has a electric foot peddle that doesn’t seem to suffer from the same problem when used.
many idea where to start looking .... fuel or electrical??.
Thanks in advance!.

 

[Timbo]

Short in wiring on the 'cancel' button

 

[jjm]

Thanks, will investigate!. Do you think it will be in the actual button or somewhere in the wiring back to the fuse board?,