heat sink came off mamba...

[BrianG]

While you're at it, you could take this opportunity to use a bigger heatsink if you have any heat problems at all. I wish mine would come off so I could do this. Is the heatsink held on with thermal tape or is it some type of epoxy?

Anyway, you need thermal epoxy (not compound or paste). The best out there is ArcticSilver. They have two types, so make sure you get Arctic Alumina, not the silver adhesive. The silver stuff has silver particles, and while it's not supposed to be electrically conductive, it does have some capacitance which could cause weird issues if it comes in contact with the FET leads.

Just thoroughly mix equal amounts of each tube and apply it to the top of the FETs. Use sparingly! Any excess will just end up squished out onto the circuit board. Hold in place for an hour or two and you'll be set!