Checking for sludge in a 2003 Aero

[cpaulpersons]

I'm in the process of dropping my oil pan to check for sludge, the car is new to me and I'm not sure on the state of the oil pan as of yet. However before I drop the pan, I've heard that its smart to take the valve cover off and check for signs of sludge in the top end. If thats not true, let me know. If it is, I want to get the cover off, but I'm not sure if in doing so, I'll ruin a gasket. What is the best way to take it off? Being aluminium, I don't dare take a screw driver to the edge to try and pry them apart.

What method have you used, and do I need to replace the gasket before putting them back together?

Also, does anybody know of pics out there of a dirty and clean top end?

thanks, Chris