Good solid unit but the Achilles heel of all GL 7x series decks are the arms, imo. Check that the lift/lower mechanism still works. Check that the arm moves freely. Check that the headshell isn't 'wackery' where it bayonets to the arm-tube. Check that the cartridge is screwed firmly to the mounting plate in the headshell. The cartridge mounting-plate is itself fastened to the headshell by a screw-and-nut arrangement which permits a certain amount of forward-aft movement. Make sure this is tight.
The drive-mechanism is bullet-proof but like all idler-drive turntables, the rubber on the idler-wheel can harden and perish over the years. Spare idlers from broken decks are frequently available through eBay.
If your '72 still has its strobe attached you can check that it's running on speed at 33, 45 and 78 using regular tungsten electric lamps, 'energy saver' lamps, but probably not these new-fangled LED lamps. If you notice a 'walking' in the appropriate strobe pattern, use a Phillips screwdriver to loosen the screw on the appropriate 'fork' and move it slightly forwards or rearward to adjust the speed, then tighten the screw.
Good luck!