Never saw or heard of that before. But in my opinion (and worth all you paid for it), I think your chain was regreased and put back on slightly off. My wheel only turns about 350° either way. I think if you actually move the boat, you will find the indicator will be off about 20° or so. The quadrant is probably hitting the hard stops above the rudder.
I once got on a boat that the owner regreased the chain. When he reinstalled the steering, he did not cross the chains in the pedestal. Spin the wheel to port and the boat went starboard. Made getting back to the slip interesting.
Turn the wheel all the way to the stop. Loosen the turnbuckles on the quadrant, pick up the chain and move the wheel until it is about 350° to the direction you turned. Drop the chain back onto the gears and go tighten the turnbuckles equally. This should get you close to center.
If you are close, you can slightly adjust wheel by adjusting the turnbuckles without moving the rudder itself.
At least I think you can do the last part. But not by yourself of course.