Can cause expensive results and a whole lot of inconvenience.
I did this, this afternoon before completing the pinwheel blocks. The bobbin winder decided it wasn't going to work. So while I was at it, I had this bright idea that I could fix it. Hmm not such a bright idea after all. While attempting to remove the top part of the machine a tiny piece fell down into the inside of the machine. My machine is now at the doctors being repaired... Thankfully I have my little Gem to go on with. I couldn't imagine going through sewing machine withdrawals.