You don't have to remove all four screws. Only the two in the middle along the back edge. There are only two screws holding the front panel down.
It is amazing how fast the chip heats up. The systems will only stay on for a few seconds.
It might be better to scrape off the heat sink compound and replace it with one of those thermal conductive pads.
The thermal expansion and contraction of the heat sink compound will eventually stress the seal and reduce the elasticity of the compound to the point where its effectiveness may become less than optimal.
It is sad to say that such an nice machine can have such a small design flaw that it will give the vendor a bad name.
I actually like my m6811 so much that I let my original RMA expire. ( I also was skeptical that I would get a worse machine back and not mine plus daily use and data files! ).
I have a new RMA and I may send it in this time because my Card Reader does not work and I pray that they don't send me back a different machine that will develop hindge cracks or dropped pixels.