I had an issue where movement would cause ram error and sometimes computer wouldn't boot it would just beep 3 times. I managed in isolate it to the bottom slot on 13" 2012 MBP. My computer was 10 years old so had accumulated a lot of dust and dirt over the years. I tried the spacers suggestion above without success so I tired the full overall approach. I completely dismantled MPB and removed the logic board so that I could clean it. I lot of dust and dirt had accumulated on the bottom side which compress air (e.g. from bike pump) cleared. I also noticed that there are lots long pins under a plastic cover for the bottom RAM slot (which connects into PCB behind the top ram slot) and there was lots of dust stuck between these. I carefully cleaning with plastic pointer and Electronic Cleaning Solvent. After re-assembling (ensuing keyboard ribbon cable with completely mated) the issues seem to have gone away.

Thanks for the guide - only suggested improvement would be to flag that it's a good idea to check inside ot tyre before re-inserting the repaired inner tube. Otherwise the thorn might still be sticking through and you might immediatly create another puncher.

It would be helpful to take this guide with words like 'puncher', 'tyre', 'wheel, 'repair', 'bike', 'inner tube', 'flat tyre' so it's easier to find. Before posting this comment a comment search did not find it: https://www.ifixit.com/Search?doctype=gu...