It should slide right in nice and easy. No force should be required. Make sure that the drivers are in the track windows and not hanging up causing you friction. Also, put some anti-seize on the splines that the brake goes on and clean her up a bit when re-assembling.
The driver shaft can still move, the rotor isnt tight either. Its like the sled pulled apart between the running bords.
The beer took over last night so i gave up but once i put pants on today im gonna try loosing the 3 10mm bolts inside the tunnel an try to get snap ring on first