Yeah same here, I do not loan tools anymore.
My dad needed to use my tractor (MF1145) to do some loader work at his place. No problem, come get it, I don't have a trailer so bring yours. MONTHS go by, and I needed it for my own work around my place. So I asked if he was through with it. He said my brother's got it. Great. Y'all don't know my brother, but he destroys everything he touches. Besides that, I was never asked if he could borrow it. So I am mad by then. I went over there, as opposed to calling, to get it. Tractor not there. It was on loan to his friend, who by the way also borrowed my brother's old Belarus and actually broke the tractor in half, cracked the clutch housing all the way around. Ruined it. So by now I'm totally PO'd. I told him to go get my tractor from his friend, deliver it to my house by 9:00 pm the next day, or I'm going to call the sheriff and report it stolen, and then they can deal with it themselves. It was at my place when I got home the next day, but the clutch is SHOT, loader valve joystick broken off, 3ph leaks down, and left front tire was totally flat.
So yes, I will never EVER loan tools out again.
I did have a 4701 on the shop a while back with similar issue, fan belt. Came to find out AFTER the fact that the operator had knocked the belt off at some point by using the tractor for a dozer, clearing timber, probably a limb or stick or log knocked the belt off. They reinstalled it but it never stayed on after that. When I got it, I removed the old belt and it would not hold it's position. Somehow it had a memory, in that it wanted to "roll over" by itself. Replaced with new belt and that solved his problem.