My 87 Westy's sliding door developed a popping noise each time I close the
sliding door. It happens when it's almost closed and makes the inward turn
to close shut. Prior to this development I noticed small bits of rubbery
plastic pieces fall out of the area. Do I need the guidepiece (p/n
251843368)? And what's involved in putting this in? Thanks.

Jean-Woo
PS. I have access to carfax again.