On Tue, 16 Jul 2013 03:55:06 +0000 (UTC), "Danny D."
wrote:

I'll see if I can stop by her house tomorrow - but - so that I'm
armed with some knowledge, have you any idea what to look for?

You have good advice already. A leak at the bottom is cause for
replacement. The leak can trip the reset button if it has one (?).

Does she have a dishwasher?

The install instructions have directions that address this. With a
dishwasher there is a "plug" you have to knock out before install,
otherwise water will backup into the opposite sink.

Make sure the air gap vent hose is mounted high on the back wall, too,

Samples:

http://www.askmehelpdesk.com/attachments/plumbing/29993d1269632734-dishwasher-overflow-vent-sink-required-high-loop.jpg

http://www.askmehelpdesk.com/attachments/plumbing/16988d1235612177-newly-chronic-overflow-dishwasher-dishwasher-air-gap-installation.gif