Rust streak by door, under boondock handle.

Robermcm

Every time it rains, my 2023 tab 400 develops a rust streak down the left side of the door, under the boondock handle. Runs the entire distance to the bottom trim. I suspect it’s some poorly rustproofed piece of the sturdy boondock handle, but removing the bolts doesn’t loosen the handle. Suspect 3m two sided tape is in use. 

Has anyone removed the handle and fixed this rust issue? Is it hard to get the handle separated from the tape? What was the cause of the rust?

interestingly, the Truma technician who recently worked on my 400 said that he is seeing that rust mark a lot. The mark comes off with paint polishing compound, but returns at next rain. It’s a pretty persistent mark. 

thanks much.