Kohler 360 toilets fill slowly

[Aggie83]

My house is about one year old and they installed Kohler 360 toilets. Everything was great at first, then they started filling slowly. The water comes out of the wall valve at a nice pressure! Very hard well water, ,so we had a softener installed. I replaced the toilet fill valve with Fluidmaster and that seemed to work. Now the siphon jet does not seem to send much water... very weak. done vinegar soak with no joy. The tank and bowl fill at an appropriate rate.

Could this possibly be a partially clogged drain? Nothing else is backing up, but the kitchen and laundry are 35 feet away and the shower goes in after the toilets. Not real happy with the plumber the home builder used...

 

[breplum]

First we would auger the toilet with a toilet auger. beyond that:
When we have a suspect issue with a toilet, we pull it, take it outside and put up on sawhorses or blocks and then fill the tank, and observe the flush.