PTO pulley help need ideas

[GWGAllisfan]

I have a B-110 with 42" deck, that was refurbished a few years ago. My father-in-law needed something to mow with so I took it to him to use. He has been having trouble with belts running off because the lower PTO pulley keeps coming loose and sliding off the shaft. The key is still in the shaft, and the set-screw is in place, and reported to be tight. All I could think of was to suggest a new set-screw as maybe the point on the old one was flat and wasn't getting a bite? Maybe go get some locktite and put on the shaft? Any other suggestions?

[rokon2813]

Double set screws if the hole is deep enough, but they do wear so a new one definitely.

[Brettw]

Mights well put a new key in while you're at it. And yes, locktite sounds like a good idea.