I've received 4 RMA replacements to date 5th is on the way.
Origional unit died after 3 months (I paid to ship)
Replacement was likely refurbished (newer date) died after 2 months (I paid to ship)
Replacement was new with all extras, died after 3 months (UPS Lable emailed to me)
Replacement was likely refurbished, did hack, died after 2 months (UPS Lable)
Replacement was likely refurbished (older date), did hack, died in 2 months (UPS Lable)
Replacement to be received.
My guess is that there is a basic design fault with the unit and refurbishing is a replacement of parts that have the same fault.
Most of the time the units fail to Prep sometimes making a ticking sound.
Warning keep records and packing box, when you start to have problems get RMA info asap - don't wait - things don't get better with time. Don't beat yourself up it's not your fault if the media did work once it should work again.
Keep all the +RWs that would not Prep they may be OK with the replacement unit. Try using a computer DVD writer to erase them first.