[RobSC]

The screen is inside the inlet to the solenoid valve, #5 in the attached file.  I thought it was missing until I stuck my finger in there & felt it.  I cleaned it & let it sit in white vinegar which dissolved the remaining deposits.  I couldn't find a 90° union so I used a 1" Sharkbite 90° fitting.  I can pop it off the next time the screen needs to be cleaned.  There's no room for a straight inline union.

This was done with the mid-bath.  The rear bath isn't going to be a walk in the park either.

The screen is the problem no doubt.  I dug into this today after reading this thread.  My Headhunter toilets were always a mystery to me why they never really performed as designed.

I tackled the mid bath toilet first. I had easy access to the solenoid located above the Aqua-Hot to cut, remove, clean and install a Sharkbite straight coupling.

       

The rear bath toilet in fact was much harder.  After removing the trim behind the toilet, I had visual but would not be able to cut any lines without moving the toilet away from the wall about six inches.  The drain line removal was pretty easy with the Fernco flex fitting.  The water supply line was tight and took a few choice words to remove.  Also, had to clip the two solenoid wires to remove the solenoid and screen for cleaning.  The screen on this one was worse than the mid bath toilet.

                     

After cleaning the two screens, the difference is night and day.  Both toilets sound like jet engines and performance to match.  Finally, I will be taking Steve's advice and upgrading my filter system for the whole coach.