Had to install new guts (Fluidmaster) in the tank of a Gerber brand
toilet. Had a problem with water spewing out between the tank and
bowl upon flushing.

We retightened every nut (flush and fill valves, the 2 bolts holding
the tank to bowl). Tried two different (new) gaskets between the tank
and bowl. To no avail.

It's like there's a hole somewhere, the gasket isn't reaching far
enough (I think it is, but not 100% positive), or ??? Never had this
kind of thing happen so I'm at a loss as to what's causing it.

Help!

Thanx
Renata

I'd take it apart and inspect the parts. Then make sure there is
no interference to the parts seating properly. If this is Ok assemble
it again and use Vaseline on all the rubber seals/gaskets. Tighten
equally.