(ET) Power sag on an E20

[Chris Zach <czach computer org>]

Quick question: Any idea why the power would be dropping on an E20? 
Basically the meter goes into the red in L a bit too easily, more so 
when the thing's been driven for awhile.

Two battery posts are slightly warm to the touch after an hour of 
mowing, the rest are fine. I know it's not a battery balance issue or a 
battery dropping too low because of my mighty battery monitor. (It's so 
good)

So where else should I be looking? Or do the E20 motors just wear out at 
some point?

Chris