David, so glad you are back!
To the question on how-to for Trilliums, go to the upper right of the page, click on Manufacturers and select
Trillium.
There you will find hundreds of threads on repairs others have done, including David. I found David and Randy Bishop postings key to my learning. There are others as well, but those two have both owned many Trilliums and done thorough repairs.
The
Trillium is a great trailer!!! But, it has some well documented shortcomings.
Windows, belly band, body to frame bolts, door hinge mounting, frame issues. But realize your trailer has already lasted over 45 years, which is a testament to the good design.
If you use the search function, be sure to search via Google.