Suburban - Rear door holdback

My 95 Suburban has the rear double doors that swing open (not drop down).
The door on the right will no longer hold open (it feels like a detent must
be broken).
What do I have to do to fix this (remove the door panel or not?) and what part do I need. And can I get this part cheaper somewhere other than the Chevy Dealer?
thanks, Jon
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