Hmm... The worst thing I can think of is once I was trying to fix a gear mechanism that kept getting stuck and balls kept getting trapped in it. For whatever reason I decided the solution was to file down a plastic nub on one of the gears... Thankfully I was only dealing with a Homerun Action table top game!
Then there was the time I had my soldering iron clamped inside the cabinet... Thankfully I didnt lose enough hair for it to be noticeable!