Toto Drake won't stop flushing

[gus13219]

I installed this toilet (ST743 ST 1.6Gpf tank) 9/2020 and it's been great except that a few times each week a flush will throw it into a loop where it keeps flushing repeatedly until we intervene. It has a flush tower with a plunger where I'd normally see a flapper. The only way I've found to stop the continuous flushing is to apply pressure on the plunger and hold it down until it's covered with water. I live in fear of someone rushing out the door after a flush and water running continuously until they return home.

I thought we were maybe holding onto the flush lever too long or not long enough and that we'd adjust habits over time. But it's happening more and more often these days and it's embarrassing when we have company.

Problem began in the first couple months of ownership and I kick myself for waiting this long to pursue it. Full disclosure we do have hard water.

Wondering if maybe we have a defective flush tower, possibly a burr that the plunger sometimes hangs up on. Anyone else seen the continuous flushing? Should I contact Toto directly?

Thanks in advance for any thoughts/recommendations.

 

[Terry]

Check to make sure the handle isn't sticking.
You can rotate out the center part and check to see what that looks like. I spins out counter clockwise.

 

[Sponsor]

 

[gus13219]

Check to make sure the handle isn't sticking.
You can rotate out the center part and check to see what that looks like. I spins out counter clockwise.

Thanks for your response Terry.

UPDATE: I removed and inspected the nut that holds in the handle. No signs of abnormality, and we have never had an issue with the handle sticking.

I removed the lid so I could carefully observe handle and plunger operation. This is a sporadic problem and it didn't happen again until last night (4 days after original post). The chain that connects the plunger to the handle lever had plenty of slack in it, so the plunger was free to drop down if it was of a mind to do so. But it was hung up. I pushed it down (with minimal force) and waited for water to fill above it to ensure it sealed properly. The toilet has flushed happily since then. Our experience has been that the problem will return in a few days.