I've had a Pioneer DVR-630-H since 2006 and ever since then it's had problems with DVDs (hard drive recording/playback has worked fine though).
I really haven't burnt/played DVDs much, so at first I thought I had gotten low-quality DVDs (even though I consistently bought well known brands, even Taiyo Yuden which I hear is supposed to be the best). But over the years I've concluded that the unit itself is at fault as it often has problems reading purchased movie DVDs (I tried a brand new DVD out of the box the other day and it refused to read it. The same DVD reads fine on my computer).

What happens with pre-recorded DVDs (purchased movies etc.) is that I hear some "clicking" sounds (the laser seeking?) and after a lot of that the tray ejects the disc with an error message saying it's an "unreadable or incompatible disc".
With DVD-R discs, when trying to record I often just end up with coasters. This seems to happen more often as I burn more on to it. If I don't fill up a DVD-R the chance of it suceeding is higher.

What kind of problem does this sound like, and what can be done about it?
Unfortunately I didn't return it during the warranty period

As for replacing the drive myself: I've picked up on a few threads on the subject, but I'm quite confused about the exact procedure. Isn't it just a matter of getting hold of a new burner (IDE I presume), or am I forced to get one of the exact same type Pioneer has used (which I assume is no longer available now that the recorder itself is no longer sold by them)?
Alternatively, I have seen a local ad for a Pioneer DVR-220 for sale cheap. Could I simply use the recorder inside it and replace the one in my 630-H?