501-2013 is the part #. Center column, second figure from the bottom.
When you have the selector plate in place there should be a follower that rides along one edge is it there?
If it's trapped beneath the plate I don't think anything will work properly. Something else though. As I remember the slow speed escapement can be adjusted by pivoting it and if it's engaged too deeply it won't allow movement of the blade operating ring.
There are two screws in the escapement one at the end is the pivot & the one near the middle is the adjustment point. For adjustment leave the one at the end snug & try moving the opposite end of the escapement in & out. It won't move much, fractions of a mm perhaps.
For lubrication, watch oil on pivot points on all the levers, a poo dab of grease on sliding surfaces & nothing on the blade housing, blades or blade operating ring. They should be absolutely dry.