I wiped the outer case off with a rag to get rid of some of the built up dust.  It didn't all come off, but enough did.  Next I checked to see if there was any apparent screws or clips I could undo.  I didnt see much other than a plastic screw around the connection terminal.  I undid that and tried to separate the top, just in case it was that easy.  It wasn't.  Next i took a screwdriver and pried carefully around the lip to see if it was clipped together.  No luck.  The lid was plastic and the main housing is aluminum.  At one point early on in life, I would have just broke the plastic, but I have since learned to avoid that if at all possible.  So next I just kept gently working the screwdriver around the perimeter until it started to separate just a little bit.  Once I got one corner loosened, I could see a foam liner.  It was glued together and split easily once I got the first split going.