nu-way snowbird toilet drain

I agree with Old-Biscuit, I think you have a foreign object blocking the drain.
Is the toilet plugged up or, when you try to drain the black tank nothing comes out?

You may have to run a snake up the dump valve. But, be ready to remove the snake and install the slinky in about .003 seconds, or less.

Did you try a Rinsing Valve?

Mine has same two (2) 45* elbows and NEVER plugs up.

You missing anything.......kids toy, comb, brush etc. ?

Need to run a 'snake' down thru toilet into black tank.

Wouldn't use Drano or any other chemical drain cleaning........toilet line is 3" so you have a large blockage. Mechanical means of clearing vs standing pipe of chemicals

Drano and lots of water!