The D300 is a great camera - I've had mine for 5 years or so. I don't think she needs a new camera at this point in her photography, but I could always use an upgrade. The ISO handling of the D300 has always been a sticking point for me.
Having said that - the hard part is organizing the unplanned expense of either the repair or the replacement. I have no idea how much work it takes to replace the little plastic tab - I think that's my biggest concern of the whole thing.
Thank you all for the recommendations - I'll give APS a call and go from there.