Kohler Toilet - Low Rim Jet Flow & Low Water Surface Area?

[Joe97]

My Kohler rear discharge toilet has little flow from the rim jets and the bowl's water surface area is low. The flush jet's output is strong as new. I've snaked the toilet checked, the distance from the toilet lever arm to the cartridge, probed the rim jets, replaced the cartridge, replaced the bowl to tank seal, checked the water pressure and flow to the toilet, cleaned the screen and removed the flow restrictor with no change. The porcelain shows no cracks nor is there water on the floor. The stack is clear. The toilet holds the proper water surface area when water is added to the bowl.

The plumber says I need a new Flushmate pressure vessel despite the strong output from the flush jet. Kohler and Sloan say it isn't the Flushmate. Before (or in addition to) replacing the Flushmate is there anything else that should be tried?

Thanks for the help,
Joe

 

[Geofd]

have you tried cleaning the jets....they will get clogged over time get something small and try to poke thru like a small piece of wire