You can return the FluidMaster and may find a replacement of it from Korky on the same shelf, get Korky's Stainless Steel Tank to Bowl Kit too (2" or 3")...those new fangled Brass Plated bolts from everyone else are almost worthless and start rusting in just a few years.
- But, as long as the Flush Valve works and just fits the tank's hole you should get the same performance as the original, assuming you don't have something restricting flow under the tank or at the bowl's inlet or even have clogged flush ports under the bowl's rim (poke those clear).
- However, you're dealing with the wrong end, the tank's flush hole size is what it is. Not flushing well is primarily related to your toilet's drain pathway or the plumbing pipe the toilet attaches to being fully or partially blocked (that all MUST be clear).
- Remove the toilet and floss the toilet's pathway with a Drain Auger, you'll also use this to clear any blockage within the plumbing pipe. If applicable, you'll need to chisel any iron plumbing pipe back to full diameter (vacuum ALL chisel debris out). Finally, you'll need a new wax or wax-free Toilet Seal to reinstall the toilet. It'll operate as good as or better than new.