Leaking waste Valves

[dochall]

We purchased a 2011 Laredo 318RL 5th wheel in the summer of 2010. Right from the first trip we have had leaking waste vavles. It is going back to the dealer for the 6th time this weekend. The black water tank has had seals replaced twice and the entire valve replaced the last time. Seems to be fixed now. The kitchen grey water tank has had the same things done but the last time out the cable broke on the new valve when opening the valve so the valve in the open position. The bathroom grey water tank has had seals replaced twice. it is now leaking and will have to have the valves replaced. The cables on the new valves seem very flimsy.
The good news this is being done under warranty but very frustrating that they can not get it fixed. Has anyone else experienced a similar problem? Is there any other solutions to fix the problem. Has anyone tried the electric operated valves.
Thanks for any advice

[Bushman512000]

The elect.Valve uses the same seals.Question is the valve in Question real hard to open?If so it sounds like a comen misalinement to Me.some times just the water waste weight will add a strain to the pipe the valve is in.Look at the way the pipe runs does it look like it is strait or kinked at the valve?I had that trouble once and fixed it useing a flex rubber joint to releave some strain on the pipe and valve.No more leaks the rubber joints are bought in lumber stores plumbing area.cut the pipe tank side of the valve have 1/2" gape install new joint do up the clamps (do not over tighten) You should be leak free if seals are not pinched if so change the seal also..Bushman the rubber will always help to do repairs down the road cut and glue is not the way to go You can do it just so many times then what?See the rubber on the pipe I moved the valve.left click pic. to enlarge

[dochall]

Thanks for the suggestion. I just got it back from the dealer so will see if they got it fixed this timet. So far it has been done under warranty. The valves are hidden under the underbelly cover and are cable operated so I can't see what the setup is. If they didn't get it fixed I will have to start investigating problem myself and maybe use your suggestion.