I had the fault with the DMR EX75 failing to record DVD's. It would make clunking & loud whirring noise & fail at about 50%
However it would read & play any disc just fine, so I figured the laser must be OK.
Its an easy fix. 5 screws to get the case off, then 6 screws on the lid of the DVD drive (these where tight so use a good quality larger handled driver to avoid damaging the screw heads).
Once the DVD unit lid is off, gently clean the laser & the rubber pinch wheel (mine was quite contaminated) with head cleaner fluid using a cotton bud.
Dry it off with a clean cotton bud & re-assemble.
Hopefully the DVD burn should now work fine, I just burnt 5 discs one after the other , after creating about 10 coasters before it was cleaned !
Good Luck
John Hemming, December 2009