I was a mechanic for many years in a niche market that requires a large investment in specialty tools. I retired 9 years ago but still do repairs, almost exclusively on my own collection but I also have a couple of past suppliers that became friends and we occasionally will bail out each other on jobs that go south.
I had a friend that owns a few of these specialty vehicles and he showed up at my house one day needing a tool "desperately". I figured he had a machine down. He returns it the next day in the box as he received it, I asked if it all went well and he assured me it did. He said thanks and off he went and I put the box back in it's place. About two months later one of my past suppliers called needing a bearing pressed out and in and did not have the tool. I told him no problem. He brings it by with the new bearing and was headed into town. I told him to give me an hour and he could pick it up. Well I get the tool that I had loaned off the shelf, open the box and pull it out and find a broken collet. I had to rob a collet, that was not correct, make a piece on the lathe quickly to do the job. I got it done but was not happy.
I ordered the replacement collet to the tune of $118 and put the receipt on the cork board. Guess who shows up about three weeks later wanting to borrow another tool,,,,I pulled down the receipt and told him he owed me $118 for the collet he broke. He did not deny he broke it and the straw that broke the camels back was when he said he did not make that much doing the job he broke it on. So not only did he break it but he was doing paying work with my tools. I told him out of my shop, no more tools loaned to anyone!!