Listening to your Dreamcast laserunit transport motor is the way to go.
If you hear wang..wang. wa wa wang wang (the laserunit reading different parts of the disc) you might wanna not be playing that foor too long.
A good example is "Last Blade 2".
In this game every yel/slash-sound effect is loaded from the gd-rom.
This is really bad for the Laser unit. But before that you'll go crazy from the screeching lensunit noises. Gimme a break!
I wonder how long a Dreamcast would last if there was a championship to be held on a Dreamcast running that game for a couple of days.
And this goes for the illegal cdr backup copy.
But it must be the same with an original
Maybe the makers made a deal with Sega so to sell off their Dreamcast stock to people that break their Dreamcast playing this game? (just kiddin')