How do you take off and put on the B pillar trim piece?
 

I previously had to take the B pillar plastic trim piece off to replace the vinyl since I did the job wrong a few times. That trick worked a time or 2 of just smashing the trim piece back on at the top but on the 3rd time it ruined the metal catch piece that the plastic pillar attaches to at the top.

Is there a right way to take the pillar off and on without messing up that piece?

1991 300d