Nite Owl replacement batteries for ROM 01 IIGS?

[Jack Countryman <jcountry@seidata.com>]

We still have an Apple II lab at school (Mastery Development) that uses
a IIGS for a server.  However, the battery in the IIGS has died over the
summer.  Without the battery, the tracking program that keeps student
records doesn't work.  So, we need to replace the battery.  

Years ago, when the ROM 01 IIGS was at its height of popularity, there
was a slide on replacement battery for the ROM 01 IIGS from a company
called Nite Owl in Mission, KS.


Is Nite Owl or someone else making a replacement battery for the ROM 01
IIGS?  Or has someone else come up with an easy way to replace those
batteries?

Thanks.