John, mine was clogged a short time ago. There was a right-angle fitting on the end of the hose where it attached to the tank. I removed the hose and could not get any water through it! To see whether the clog was at the fitting or the in-line check valve I cut the tubing about 6" from the fitting. The water flowed fine! I used a flat-blade screwdriver that would go inside the tube and started twisting it. You would not believe the crud that was inside that tube up to the connector!
There was a small amount of it in the nozzle inside the tank too. I got it all cleaned out and flushed it out with a water hose with straight stream nozzle.
I had become accustomed to the sound when I would flush the tank. I was amazed when I tested it! The sound of the water spraying inside the tank was at least twice as loud! No doubt it had been partially clogged ever since we bought the MH two years ago!
The question then was what had caused it to clog in the first place? I thought there was a screen inside the black tank flush inlet in the wet bay. Guess what, there wasn't! I immediately put in a new hose washer with the filter screen. That will never happen again!
Hope yours turns out to be as simple!
Good luck, happy trails, and God bless!