Also make sure that the absolute tip of the CB has some clearance on the rear of the
gasket. If the longitudinal "cut" does not extend far enough past the tip of the CB then
you will have issues getting the CB started down, but since you can step on it and push it through, that may not be part of the problem.
You need to either take the CB cassette out of the board, or have your dealer do it and
make sure all the side plates that support the CB and smooth and fair.
Also check that the pivots are clean and aligned with each other. The pivot bearings
should be a close rotational fit on the pin (s) in the CB.
Hope this helps,