This is the toilet I have. It bubbles up when flushed and is not pluggged.

Remove the toilet & have a plumbing company power snake
as much of the entire homes waste drain as possible

Maybe clogged inside the home on most runs & also out to
the street,have them do as much as they can, out to the street

Remove all toilets, so they can do good job & you can check &
clean them from under it

Have them run a camera down ALL drains & to the street

Perhaps it is taking a long time to fill the cistern, take top off and see if it's filling after flushing, if it's slow and pressure is ok it is likely to need a new diaphragm in the filling valve.

Take a close look at the Geberit TM seal...mine had air bubbles in it that prevented a flush seal...and heance a slow leak that caused it to fill-up many times a day and night...see my issue here: https://pierrebridge.wixsite.com/fixit.

Remove the tank. Remove the flush valve and replace with a new flush valve kit. May need to change tank seal also.

Hi,
Change the flapper with a generic one that will fit that toilet... the OEM flapper is **** and it does not allow for a good flush either...

heatman101

Hi, you need new Mansfield 210/211 flush valves. They can be found on amazon.. here: Amazon com Mansfield 210 211 seal. I hope this helped you. Cheers

Have you checked it out for any blockage in the toilet or drain line.

You could try a 6ft auger to try to remove blockage from toilet.
If it is a drain issue it is either blocked somewhere or the vent is not working correctly causing it to get air bubbles.

Check you tank for proper water fill level up to marked line. Also make sure fill line from fill valve is connected to overflow pipe to fill bowl up correctly.

Not enough water in tank will affect the flush.

That is a tricky one. Tighten the tabs, twist into place, then tighten a bit more. They are a pain in the a$$, but with patience you will get it done. Good luck

You got a bad seal for sure.  Even though it looks like a good seal.  Open up the lid and see if you got any little bubbles floating up from around the seal or listen for a slow water drain around the seal.  Go to Lowes and tell them you need a Korky flapper.  Their the best thing since sliced bread and peanut butter.

the flush neck must be pitted or someting, the part that the flapper sits on that needs to be replaced.