I don't know if I'd call myself a guru: I'm just fearless enough to rip into any equipment that comes into the room, warranty be damned!
This problem is very odd. I *only* use the analog outs from my D1624 thus far, and they are indeed always on. Even with the balanced I/O option, the single-ended RCA outputs still work, which can be useful for dubbing off to cassette. I go straight from RCA out on a track to cassette quite often: the levels are -10dB nominal, and this should work just fine on your D824.
One thing that is a tad bit confusing about the 824/1624 back panel, though. The outputs and inputs are in reverse order: they got from high to low numbers as you go from left to right. Don't take this wrong, but are you sure that you're picking up the correct outputs? You might be plugged into 7/8 when you think you're picking off 1/2. Just a thought- the numbers are small, and if it's in a rack this is an easy mistake to make (and you can guess how I know- I wasted about an hour on this when the machine was new...).
If that's not it, and there is never any signal on any of the outputs in play mode, then you probably have a wiring problem in the box. If I recall correctly, the converters are on a separate daughterboard, and the header connector that should join them to the main board may have become displaced in shipping. I have the balanced I/O option, so I didn't pay much attention to the single-ended I/O, so I could be wrong about this, but it is something to check- there are no less than 4 or 5 separate daughterboards joined by various header cables in there.
This would probably be an easy fix, if you were willing to dig into the box. But if you are never getting any output on those guys, something is definitely wrong with the unit, and it should be a candidate for warranty work. Attempt a fix yourself, or contact Fostex- your call on which way to go. Fostex's warranty policy is "you send it to us, and we'll ship a replacement whenever we get through with receiving yours", which can lead to significant downtime...