For this you will need a formatted tape with nothing important on it (The machine will tug and pull on the tape.) This will take approximately 5 minutes.

With the unit off, hold REW while powering on. It will kick the tape out part way along the way, and make many noises while it tests the brakes and motors.

If it passes, it will only briefly say PASS, but if it fails, the fail code will stay on (So it's OK if it doesn't say FAIL).