I tried to empty the grey water tank after emptying the black water and found little resistance from the handle movement and no movement of the valve. And the tank was quite full! At least we weren't trying to leave that day, the weather was good and there was a clean washroom close by (we're at Santa Fe Skies).
I searched Foreforum, the Internet, and YouTube; talked to a FF friend (Barry L), and had a mobile repair fellow come by to look. The handle had pulled out of the valve blade and the way forward was to cut the valve top off and pull the blade out to empty the tank before replacing the valve. (Helpful YouTubeVideo (https://youtu.be/dNYl86RJiuI?si=nMtGWrabYYaQAy07))
A few trips to Harbor Freight and orders from Amazon, much contemplating and a little procrastinating saw the successful replacement of both the grey and black water valves.
I cut the top off the valve with a rotary saw blade on my Dremmel; it took a while (the Dremmel is a bit underpowered for this work) and had to make a few cuts, getting closer to the blade each time. I drilled a small hole in the end of the valve blade, inserted a screw, and pulled/levered with pliers to open the valve part way. Not much water flowed past the blade into the utility bay. It was a relief to have the valve opened part way and allow us to use the water in the coach again without having to flush it down the toilet.
I didn't want to put too much pressure on the pipe downstream of the grey water valve to provide enough clearance to extract the old valve and put in the new one, so decided to replace the black water valve as well. That way, with the bolts for both valves removed, I used a spreader between the downstream piping and the black water upstream pipe to open enough space to remove the two valves and replace them with new ones. (Valterra T1003VPM (https://www.amazon.com/dp/B000BGK22E?psc=1&ref=ppx_yo2ov_dt_b_product_details))
The nuts and bolts (11mm wrench/socket) were surprisingly easy to remove after the first turn or two; not so easy to get them back in securely in the hard-to-reach positions. I reused the nuts and bolts as they showed no signs of rust after 27 years and thought they might be better quality than the ones that came with the new valves.
I used plumber's grease on the gaskets to help hold them on the pipe flanges while inserting the new valves; even so, it took a few tries for the black water valve because it had very little clearance between the pipe flanges and they were not parallel to the valve when spread apart. I reused the valve handle extensions as they are the correct length.
Perseverance and many coffee breaks to rest a bad back paid off. Hopefully good for another 27 years! The utility bay is even a little cleaner behind the wall.
A few more photos
Glad it worked out. That happened to me as I was dumping the gray tank before pulling into the service bay....perfect timing for me.
As a preventative I replaced the gray and black valves again at 5 years.
All's well that ends well. I replaced both valves on my 1981 Foretravel.
I guess if anyone has a valve that starts to get stubborn, stiff, or starts to leak, the key is drain and flush the tanks and replace the valve(s) before being faced with an inoperative valve and a full tank.
Hopefully an exact replacement valve is available.
Always fun to play with the gray and black tanks isn't it? In 2020 I replaced both of my manual valves with Lippert electric valves, that was fun. Also replaced the third valve with a manual valve and went with the Lippert waste master hose. much superior hose to the usual bayonet fitting hoses. After 2 years the handle on my third valve broke and before that the electric valves were acting up. A suggestion was given to me by another owner to get some rubber 3 in connection hose and that should fix it. I bought the parts but have yet to do that job but I may do it in the next couple weeks while I'm here in South Dakota.
The biggest problem I have with my system is not the valves or the hose but the ventilation system for the waste tanks. I suspected it had something to do with the previous owner getting the basement repaired in nacogdoches. I already found that when they reconnected the vent it blocked the black rinse. It wouldn't surprise me if something is funky with the vent. You can hear it how it's struggles when you first open the valves, before finally getting some air coming in behind it and drain better. Personally I think that the black tank should have had two vents and the gray a separate one for a total of three. Just not enough air flow through them to perform like they should.
Anyway good write up on your replacement and pictures are always great.