PS3 Freezing when bumped?

Hello Everyone

I have an older PS3 slim that has been having some strange freezing issues.

When I first power on the unit, it does fine. After it starts up, if you touch the system anywhere, it freezes. Any slight shake freezes the system.

Things I have done AFTER problem started.

1. First replaced HDD, when that didn't help, replaced with SSD.

dissembled PS3, loosened heat-sink screws and re-tightened, alternating between screws every 1/4th turn to ensure evenness.

3.Modified chassis to allow better airflow above CPU. (This actually helped. The system no longer freezes by itself, only when bumped.)

4.Thoroughly cleaned all dust from chassis. Unplugged ribbon cables from BDROM to mother board and re-seated.

Thank you for whoever shares their