Yea what shaft speed monitor you taking bout?
Cause if it's the overhead "Low speed warnings" see if a wrecker has one
Or do you mean the Corner Post Monitor? that has the Engine RPM, Header Shaft RPM, and hours in it?
I'm having the same problem on a 9500. The tailings elevator light buzzes on and off with no load on the machine and the clean grain light buzzes at the slightest loss of rpm. We just changed the elevator drive belt and it's still the same. Any ideas?
I had similar promblems on a 9400 in the fall. Started with low voltage warning, which turned out to be a corroded ground strap by the batteries. Then under load (accelerating at the headlands, or uphill with grain tank 1/2 full or more, the tailings (most often), clean grain (second most often), and auger conveyor (least often) would come on for a few seconds. Belts all good and shaft speed sensors all looked good, even did continuity check for each circuit at the overhead control board and all harnesses good. Tested one solution on the clean grain that I read in a post. I picked up another magnet assembly that goes on the shaft and used the half with the magnet and combined with the other existing magnet half. This way the sensor sees 2 pulses per revolution. It worked well so I'm probably going to do all of them that way before 2014 harvest since neither I nor the dealer found any other problems. I don't like that I now won't know if a belt is slipping badly, but I will still know if a shaft stops spinning which in my opinion is more likely. Only my second harvest with this combine, and the first one that loaded the machine at all (60 bu corn in 2012, 160 bu corn in 2013).