2 NEC 3500AG's

Well, i was having firmware problems with 1, but i flashed it back to the offical 2.17, which seems to be the best for me. The good drive will read a DVD in 5 minutes with DVD Shrink. The other with the same firmware reflashed takes 20 minutes. Is there a way to restore the burner to factory conditions? why would this rip take longer?

and now it freezes on audio CD burning!