210 rear window repair?

[Carleton Hughes]

Here are some pics of my '98 E300 rear passenger window parts,damned plastic just went potto.

While I truly enjoy the comfort,performance and economy of this rig,I'm ever the pessimist where plastic and rubber are concerned,as they have been the cause of the majority of my woes.

Is this "piece"available?or do I have to fashion my own out of nylon and drill&tap the steel backplate?I fully understand how the system works,by the way.

I am generally NOT given to histrionics but I'm like to blow a gasket if the whole window assembly must be ordered. Any advice????