The original PlayStation doesn't have built in features to indicate when something goes wrong. According to Sony, the system can just stop spinning the disc, leaving you unable to play your favorites. If you can't stand the thought of leaving your PS1 games to collect dust, there are a few tricks to try to resuscitate what might be a dying machine.
Open the lid and isolate the small depressions which the lid's plastic forks press down when the lid closes. Press them down with a pencil or screwdriver. This lets the system know the lid is closed and it is safe to start running.
Remove the disc and power off the console. Dip the cotton swab in isopropyl and wipe the lens carefully, but thoroughly. Place the disc back in, power the machine, close the lid, and hold the lid down again.
Remove the disc from the console and isolate the laser. Gently nudge the laser's house toward the central console. If the problem was a misplaced laser, the disc should run again.
Place your hand on the central spinning console and press down firmly, but not against resistance. If the central platform returns, but a little lower, power the system again.
Turn the console on its side and power the system. If the game loads only when on its side, the central motor is broken and must be replaced.