Old Mansfield toilet

Once the handle is depressed, the white canister goes down too quickly and thus the flush is cut short. The only way to get a full flush is to hold the handle down throughout the entire flush. I just replaced the red valve which seals nicely, but that didn't solve the problem. Any advice?

 

Depends on how old the toilet is...most modern ones, and some older ones intentionally do not empty the tank when you flush.

Does it evacuate the bowl? IF it does, may not be something to worry about. Maybe post a picture of the tank's insides.

 

No, it does not evacuate the bowl. The flush is so quick, that no waste gets flushed down unless you hold the handle throughout.

The column "piston/canisters" does not stay up more than a second.

 

If it is a older it should use the #210 flush valve and mostly the #42 handle. You can compare what you have to the photos in the link.

https://mansfieldparts.com/products/man-210-1112