This reminds me of the time a few years ago when I sold someone an external CMOS battery for his motherboard. The clock in his computer reset every time he shut down so I told him he needed a new battery and at that time the only way was to install an "external" battery pack. I did it all the time and it never occured to me that it could be done wrong so he cae down, bought the battery and I gave him a 1 minute "this is how you do it" speech.
He called back about an hour later and told me he "blew up" his computer. I laughed it off and he asked to bring it down to the shop.
When he arrived I saw the case had literally been blown off the computer, screws ripped out, motherboard split in two.. he had installed the battery backwards and it had exploded.
Thank goodness he was ok, but that did teach me a lesson. Something that you do every day in your job may be easy to you but that does not mean its easy for someone else. Checking polarity was just something I knew without thinking about it and it never occured to me to mention it to him.
now that I have rambled on about my story I am sorry to hear about your incident with the fiddly bits springing loose. Maybe while he is in there he can give it a good cleaning or something as a way of making it right.