Frank Condelli said-

>> Nine times out of ten it's the brake or clutch  switch.  They need
adjustment after all these years.  Go figure  ! <<

  In my case, leaking brake fluid from the clutch slave cylinder
dissolved the white plastic tabs on both switches, but there's still
plenty of adjustment left to get them to work.

  And if you're on the road and don't want to take the time to get out
the toolbox, shims are good for a temporary fix.  Folded cardboard and
duct tape worked for me.

George/ATL