I talked to the guy that works on the sewing machines and he told me you have the worst plate there is to put on. He told me you have to loosen the screw and cock the plate to one side and finagle it in like that. He told me that he has put hundreds of them on and each time he spends 15 minutes or better to getting it on. Also the supplier told me there were no issues that he knew about the plates and that they were a pain in the @%$ to put on. So you might need to back up and punt on the plate. Apparently you own one of the most stubborn machines to play with.
Billy