I fixed my accordion with basically only my brain! For those who havent looked inside of an accordion before, it's terrifying but it makes sense. One of my keys were stuck for the longest time and I had absolutely no clue why. I was about to call a friend I have who repairs them, but I started to unscrew the back panal anyways. The inside of an accordion is several rows of pins and rods, some overlap. Basically my problem was that one of the pins sticking out got stuck under one of the rods, which was keeping the button down! 
I love fixing instruments :)