Thanks for the reply Zeeb - sounds exactly like what my superdrive is doing

.
I've taken many things apart before and got them back together and working, including PC laptop computers. But somehow, the process of taking apart my MBP scares me and I've heard quite a few horror stories too - most notably what happened to Alex Lindsay from MacBreak Weekly.
The options here seem to be:
- live with it and/or buy an external DVD writer for backing up
- buy one of those new blu-ray drives and put it in myself (risky - plus we don't really know whether blu-ray will ever take off and whether the price of blanks will ever come down)
- flog the entire machine to ifixit for parts and go and buy a new one
Paying someone else to replace exactly the same drive for 500USD doesn't seem like good use of money. Especially when matsushita drives are known for being picky about media even when they are working properly.