Hi Bonny, 76 was a good year for Trilliums, they had the design mostly worked out. The only major improvement on the 1300's after yours was that they changed the 9" roof vent to a 14" vent. I would love to see some pictures.
There are five items to check on all Trilliums:
1) The axle
. If it is the original, then it's on the order of 40 years old. They age. After several years the rubber gets very hard and the axle
no longer has any travel, or the rubber disintegrates and the axle
sags. Get a new one, with brakes
2) The door. The quick and dirty fix for door sag is to pull the door off, but leave the hinges attached to the door. Fill the screw holes with resin, and glass, tape the door back in place and use the holes on the hinges to drill new mounting holes. This is at best a temporary fix. This thread shows the best fix I have yet seen:
Trillium sagging door repair
3) The belly band. Due to how the top and bottom half of Trillium
trailer are joined, they eventually leak, and the belly band falls off. This is a complex repair:
My First Belly Band Thread
My Second Belly Band Thread
4) The frame bolts. These hold the cab to the frame. They always rust out. Some disintegrate completely.
5) The windows
. The butyl tape gets old and the seal is compromised. You pull the windows
and install new butyl tape. This is actually kind of easy, unless you also have to replace the plywood frames on the inside:
My first Trillium window thread.
Manufacture dates on older trailers are occasionally inaccurate. Maybe compare your serial number to this list, and see where yours fits in:
I started this list because I bought a Trillium that I was told was a 1979. I knew that was wrong, but how to figure out the actual age?