It depends a little on the exact symptoms,...
Here are some basics:
1) You have to make absolutely sure the tape is threaded properly.
2) When you lift the RH Tension Roller/Arm assembly, the Capstan should spin.
3) You may want to open the top cover and check all the fuses.
4) After checking the fuses, you may want to check that the circuit cards are properly plugged into the motherboard. Remove and reseat them, if necessary.
These 4 tips usually cure most of the problems you're likely to get, right out of the box. Try them, and report back. Maybe some more detail of the problem would help in troubleshooting. Once you get the 388 fully functional, it's a great unit, second to none in self-contained 8-trackers. Good luck! /DA