AMI mech #500 adjustmen

Is there anyone out there who's done an adjustment on the rack of the model 500 mech? All of a sudden when it goes to put a record back the record lands on the rack is prevented from completing the return procedure to the proper slot. I have to manually twist the record and clamp so that it puts the record away. This doesn't happen all the time and I'm not sure if it happens to the same records. I have a copy of the manual and it mentions a screw on the front end of the rack but the picture of the mech isn't clear. Any advice is greatly appreciated.