Might read through this thread.
Solenoid failure is common.
Procedure for replacing 100 series(98 and up) starter contacts - https://forum.ih8mud.com/threads/procedure-for-replacing-100-series-98-and-up-starter-contacts.9117/
It's not hard to change the sunroof seal, just a couple screws and the glass comes out, and you tightly wrap the new seal around it with a little adhesive.
You're also forgetting about the common leak spot of the bolts that hold the luggage rack...
I guess I don't stick my head in here like I used to. Almost two years????
Did you wind up making some? And out of what?
I would think the Delrin would be too soft, but some 6061 aluminum would probably work great.