I got that alternator working on that Oliver combine today. The alternator checked out OK,so I ground the paint off and remounted the regulator. Didn't work,so I put a new one on it. Still nothing. Checked out the wiring diagram for a 1550 tractor in the I&T maunal and it showed the guage being wired different than the combine was. The combine had the ignition wire and wire to the starter hooked to the same side of the guage. I switched the starter wire and alternator wire around on the guage so the alternator wire is hooked with the ignition wire,it worked. The things you have to trace down sometimes!