u/Im_W3ird

I recently purchased a Xbox Elite Series 2 off of eBay and everything was pretty much flawless. I decided to replace some of the controller parts, but when I put everything back together that's where I realized the start and select button were extremely mushy. Now I basically have to push them all the way down for them to register. I tried searching online but no luck. I even opened the controller up again to see if there was anything wrong but I didn't see anything out of the ordinary. Is there a reason this happened?