DT, thanks a lot for responding and for your advise.
I haven't gotten to it yet, but I would try my luck with fixing it before spending money on new drive. In case I am successful with the fix, I will post it here.
The upgrade idea is certainly tempting. You are absolutely right that the MKIV looks (and I am sure performs) much better, but the upgrade is a bit expensive.
I understand there would be a need for both the DVD drive and the screen, right? I did a little bit of searching and it looks like the DVD drive can be purchased for ~$600, and ~$900 is needed for the screen unit...