Rear 1/4 window plastic trim

[Leeroy]

OK, so the plastic trim for the rear left hand side 1/4 window of my 87 RX sedan has finally decided to crack in half and part company with the rest (And ugly is how it looks!).

 

Sourcing another trim piece should relatively easy, however, I have no idea how to remove it from another car without breaking the piece again.

 

Is there a simple solution? It almost looks like Subaru meant the piece should never come off once it left the factory!