Now THERE is a serious rat (project)! But, since it's a Garrard, it might surprise you and still work! I initially thought the arm was broken, but on a more careful view, I see that the headshell has been pulled out, but arm looks OK. These old Garrards are really tough and hard to break.
Where did it come from? Somebody's barn? Somebody's cellar? I think I see vermin droppings and a little rust. I had vermin living in a speaker for a while. They really liked that damping material. Now THAT was a mess!
Looks like it needs a pressure washing just to start. I'd check to see if motor spins, etc. and clean off the sticky grease. But you probably know that already.
Congratulations! I think when you wash it off, everything will improve considerably. Paint still looks pretty good. It will give a psychological overhaul when it's clean. There was a period of time when I was repairing stereo gear. I'd get these nebulous complaints like, "It just doesn't put out like it used to." I'd bench test the rig and it would be completely to spec. Then I would clean it off, using a toothbrush in the flutings on the knobs and Q-tips in the corners, so it would look great. I would say I "tested and adjusted" the rig, and charge the guy for my time. The customer was always satisfied, and always said the rig sounded better, even though the measured performance was exactly the same as before. Clean is important.
Congratulations and good luck from the old pressure washer!