Looks like you may have a leaking fitting.
That's what I have, bought the kit in 2006. Blueprint page #27 shows the same.
500 hours in 10 years. that's not bad. You're doing better than me.
Those are reinforced weldements ….NOT the new style …..RVATOR had an article from VANS on that problem and fix on older style weldments ….I have lots of pictures of broken older weldments and the fix but can’t post them sorry