This is an awesome thread. I suggest you carefully read it all if you are having F11 errors and see what makes sense for you. The root cause of all the shenanigans is the incredible vibration of these machines. If yours is more than a couple of years old there are 2 mandatory things to do and this fixed my machine the first and second time over the years that the problem surfaced and in both cases for a couple of years. Remove the three or four screws holding on the top and take it off. Find the CCU in the cream colored box at the top back of the unit and mark all the connectors with a Sharpee A, B, C,....AA etc and of course the box itself with the corresponding letters. Take lots of pics with that smart phone too so you can get it all back together. CAREFULLY remove the connectors and avoid breaking off the retaining tabs. If you do, hang onto them and you will need to glue them back on. Remove the box and the board inside. You will see on the connectors that the vibration has fretted little craters in...