ORIGINAL: causeitflies-RCU
Dave, is it sticking on the compressor nut? If so try a few drops of electronic/tuner cleaner on it and let dry. WD-40 will work too. If it's buzzing does it do it right away or after the engine picks up? If it is buzzing after the engine picks up, the turbine could be over-running the starter motor because it's not disengaging in time...hard on starter motor bearings.
Mark,
I pretty sure it is worn out. It won't even spin the turbine up fast enough to begin the ignition sequence. It isn't sticking. The Bendix unit working properly.
Dave