Toto - Water Doesn't stop running

My toto, not sure of model, flushes and fills fine. But the water keeps running through the tube on top.

How to fix?

Is it overflowing and running down the overflow tube or not reaching that height?

If it is going out the overflow tube because the fill level is too high, the valve needs service. If you have the Korky valve, you can take it apart and possibly clean it. If that doesn't work, the seal cost about $2 (at Lowes). If it isn't the Korky valve, you may need to replace the fill valve.

If it isn't reaching the overflow, but the valve is still running, it's probably the flapper valve leaking, and the fill valve is just doing its thing trying to keep the level up. Replace the flapper, but first check to make sure it is not the chain caught underneath the lip or that some crud is not caught on the seat where the flapper seals. The flapper valves are also available at Lowes, or likely your local plumbing supply house.

https://terrylove.com/korky/

thanks - I'll give it a try

umm yeah..I had this problem
You can replace the Fillvalve or do what Jadnashua recommended..
Possible Causes are: Fill Valve, or Flapper.