I wouldn't say the case is doing nothing, just that the heatsink plate is not pulled against the case as well as it could be for maximum surface area for thermal transfer.
The case did get hot in the areas of the heatsink on the side at 37 amps, I did not notice the one on the backside and how hot it got, or did not.
I just think the arctic silver between heatsink and case will improve heat transfer.
I'm kind of glad it is not there now as it is messy stuff and I will need to take the circuit board from the case again to pull the trim pot and solder in new wires leading to the new pot. When reassembling, I hope to install the grease. but the heat sink must be slid into placewhich would wipe much of it off, unless I bend the mosfets out of the way then push the heatsink into place, then have the 2 screws pull the heatsink tight to the case, then the through bolt with spreader bar to pull mosfets tight to thermal pad and heatsink.
I am uncomfortable bending things on circuit boards, but I imagine as long as it is not done over and over again and done slowly it should be fine.
