Èaster greetings to all or happy safe Sunday -whichever may apply.
Timelord, I don't believe there is anything wrong with what you have done of with you if you have successfully done this numerous times!
Something tells me that it is not your keyless works issue if you have checked all the parts and see nothing wrong with them. Something is interfering with the top part of the jumper spring (U section) and where it puts pressure against the yoke. Check underneath the yoke and if I recall correctly there is a hole where the balance bridge screw threads in from the other side. I have seen the wrong screw placed in the balance bridge which sometimes can protrude the too plate on the other side and just tilt the yoke from sitting flat on the movement! On the process of elimination this would be the only other possibility which may be causing this headache. It might be a long shot, but check it out and let us know? if I were to wager on this, I would put my money on this as being your problem! Good luck!!