Tomorrow I'll be looking at an AMI "I". (one of my very favorite jukes)
Anyway it won't reject the record. About 3 years ago it had the same problem and I think I replaced the tone arm cancel switch. Worked great for 2.5 years. Same thing. Went to see it and voila, it started working before I got there. Tested the switch over and over and it's good. What the heck, I replaced it again and tested the new one real good. I don't have the schematic in front of me but I went over all I could think of. It kept working for 6 months then again it won't cancel the record. I should have posted this a week ago but I forgot. I'm scheduled to go tomorrow and check it out. Any tips anyone? Those schematics are hard to read, and offhand I forget if that manual has the "schemagrams" which are often misleading. Thinking of it now, my manual might be for a model J, but I don't think there would be any difference in the cancel circuit.
The one thing I've seen a few times is when the cam switches are dirty and the motor runs loading a record and travels until the motor binds and gets stuck, but it's not that. Also the bridge and cap have been replaced.
Thanks,
Tony