Most of the seat belts have failed or jammed. Dust getting into the vertical buckle is Jammed up the internals,
Spraying oil into them is a big no no as it just makes a good mess onside mixed with dust, so we spray with brake cleaner and blast with air. But it keeps happening, really bad safety issue.
The three point harnesses on the old GS Moons were much better with horizontal buckles so may look at converting to harnesses.

If your having a lot of problems with them than it does sound like a good idea. My 4 points do get jammed up too. The original ones were really bad. Wouldn't let go. I caught myself reaching for a knife a few times.