Forgot about this, my DH reminded me. When we bought this 5th wheel we had trouble with the electric dump valves. After being worked on several times and still having problems, we had the electric valves removed and manual dump valves installed.
Well that repair shop cracked both tanks and didn't tell us. They put some caulk on them, and it lasted a few years and then started leaking. Well Caulk will not last on something used to hold liquid. But it lasted long enough for the repair shop to go out of business so we had to have it fixed ourselves.
Wish we had known when this was done so we could have made them replace both tanks or fix them correctly.
The good news we do have them fixed now with plastic welding and hope it will last.