@sidehack is there really no thermal pad between the "backplate" heatsink and the PCB board? Was that by intention? If not, what would be the recommended choice from your side in regards to thickness and thermal conductivity of such thermal pad? And would that give some significant cooling benefit at all?

If that makes sense, I am tempted to do that. Unfortunately, I didn't check the heatsink dimensions back then when I replaced the fan. Can you please share these, so that I don't need to unscrew my unit again.