I have an FP24 which I sent to Sound Devices for checkout and repair this May. They replaced the return-level pots and the limiter threshold pots, "confirmed unit is at production spec, passed all factory bench tests" and the total was $76.76 plus shipping. Turnaround time was about two weeks.
I called Sound Devices service department today, and the very nice person I spoke with said that $75 is the minimum bench fee for anything that comes in. It seems that they were more than reasonable on your parts!
I think I'm going to hold off on sending it in for now until I actually get my hands on it myself. Being that it's an eBay purchase, I want to make sure nothing is obviously broken or different than advertised in the event I would need to get my money back.
You and others here have successfully dissuaded me from using the XLR outputs with my M10. I had mistakently thought the FP24 had a mic/line level switch on the XLR out, but it seems that's only in the later versions. I'm curious - what equipment DO you tend to run off of those outputs? I'm thinking of pro-level gear meant to accept that kind of level, and nothing portable springs to mind other than Sound Devices own mixers and recorders which already have their own preamps.
A couple of the concerts I record every year are also covered by our local TV station, who has great video production but terrible audio. (As in, one SM58 set up on a stand next to the center camera. I'm not kidding.) I usually give them the file off my M10 afterwards, which they use for the final broadcast. I'm wondering if I could just give them a direct line feed off of the FP24 instead.