Nah. I have a Macintosh Plus with a dead battery also, and the only noticeable effect is that the date/time reverts to something like 1/1/1904 at 12:00 am every time I turn it on.

Capacitors can be damaged even if it's not visible. A component blew on my Macintosh 512k's analog board (causing it to do nothing whatsoever when I try to turn it on), but despite my best efforts to find the component that popped, all capacitors, transistors, power supplies...everything looks absolutely pristine.

So appearances can be deceiving. As long as you're not afraid of lead exposure (which I am, unfortunately), it would be wise to replace all of your capacitors. I hear that soldering isn't all that hard once you get the hang of it.

Hope I helped,

-Apostrophe