Maruzen m1100 shell feeding issue

[SGT-Snail]

hi, been having a bit of a crisis with my newly acquired m1100. firstly I had the issue where the trigger got stuck and I had to strip the gun to fix it. thankfully I managed to fix that.

but now the shells are not feeding at all. when the gun is cocked back only one of the little lips moves but the other does not seem to move at all causing the shell to remain in the tube....however you can still press them both in manually so they are in correctly. this wasnt an issue at all prior to taking it apart. So what have I done wrong?