PRAM Batteries

Exactly.  Any battery can leak given the right conditions.  The Maxells appear far more prone to doing so, but given the potential for very severe damage I think "remove all PRAM batteries" is the best strategy.  Apple isn't making any more logic boards for these, and even if you can repair the damage it's likely to be a real pain, and the physical appearance of the board will suffer (and as we all know from http://www.folklore.org/StoryView.py?project=Macintosh&story=PC_Board_Esthetics.txt the appearance of a Macintosh logic board is quite important).

Curse you DagonKid!  That link is an entry into a hole from which there is no escape.  I love reading those stories and simply can't stop.

Thanks for reminding me about those... and also thanks to Garrett for re-reminding us about the PRAM batteries.

The Maxell's explode, they don't just leak.

i find that non climate controlled conditions can massively accelerate this blow/leak condition.

The annoying part is the systems, both Mac and PC, that won't boot without a valid PRAM battery,

I just take em out... I've had some Color Classics that are finicky about not booting if there is no PRAM battery.. For the most part I take em ALL out and I use a label machine saying "NO PRAM BATT" stuck to the machine. Sometimes you leave them in and you forget then put the unit in storage it's all luck from there!!! And perhaps as Uni said environment may attribute to the leak/explosion...

id rather just leave them out and use the network time extension. 

Done... 

Any luck getting that corroded board to work? I have the same problem and am hoping to revive my classic. So far all i have done is a cosmetic cleaning. I see corroded diodes on the back of the board and corroded traces on top.

Also, will it run with the battery case completely removed if all else is functional or will i need to find a new one?