Thanks for the additional info. If it were my unit i would not hesitate to take it apart.
"...wearing the gear on the shaft, causing it to fail", Cause what to fail, the engine or the pump? The owner will be glad to hear that. The upside is he does not use it but once in awhile. The sliding sleeve is nice feature....not.
FYI - I was raised just up the street from you, in Little Chicago, Peoria. Before my time that was it's nick name it had earned, and it was not a compliment.
Thanks again.