Could have been pour maintenance by previous owners....let the turds get hard, and they just blocked the drain pipe? Could be some piece of the tank that was drilled for vents/fill pipe, that fell into tank, and not taken out when RV was built, and has finally gotten lodged in the drain.
In both cases, I'd see about getting one of those fittings for the discharge, that you can hook up a garden hose to, to flush the tank and line.....and then back-flush the water into the tank.
You may want to throw a towel over the toilet....just in case!
😞Good Luck:)
Bill & Claudia / DD Jenn / DS Chris / GS MJDogs: Sophie, Abby, Brandy, Kahlie, Annie, Maggie, Tugger & Beau 🙂RIP: Cookie, Foxy & Gidget @ Rainbow Bridge.😞2000 Winnebago "Minnie" 31C, Ford V-10
Purchased April 2008:B FMCA# F407293
The Pets