I have a Sony RDR-VX500 combo DVD/VHS unit, that I purchased new a few years ago. While we rarely record DVDs with it, the playback functions get used quite a bit. The DVD drive has suddenly refused to read any discs - either DVD or CD. The VHS side is fine. All menus and such work, etc. Just won't recognize anything in the DVD drive. So I am suspecting a drive failure.

The DVD drive is a NEC ND-2500A (built in october 2004.) It is apparently just a normal IDE-style drive. Based on some internet searches, it seems some have been able to use other IDE DVD drives in the box. (One posting on a different forum from a couple of years ago mentioned a Toshiba SD-R5372 as a possible replacement.)

So my question to the group is: rather than watching ebay for an older drive (e.g., another ND-2500, ND-2510, or the Toshiba drive), what upgraded IDE drive would work in this unit?

I like a lot of the features and the form factor of the RDR-VX500 - so would prefer to just swap the DVD drive, rather than trashing the whole unit.

It really depends on how tied into the firmware the drive that's in it now is.
It may only allow 8x or less burns max, only NEC based drives, only that particular drive or it may not care at all as long as the drive fits and the cables are the same, plus the jumpers set correctly.
If you have another IDE based burner handy that does at least 8x speed I'd pop it in and see what happens, worse thing is it doesn't work and sounds like your at that point all ready.

Yeah, those are the sorts of things I am wondering about. It seems like there should be some newer series of drives which are 'upward compatible' from the ND-2500A, (and not necessarily from NEC.) From what I am gleaning the NEC ND-2510A is one such upgrade, though a pretty small one.

The 2510a is just a 2500 with newer FW installed.I upgraded mine when it was new and did one of the first DL burns around with the Best Buy DL survival kits, blanks consisted of one DL verbatim and 8 regular plus medias and a few RW for 30 bucks.