Based on what I've read, this typically occurs when it was not installed properly.
Gerber has an online parts catalogue including a sales locator. Just Gooogle 'Gerber'.
Best I have seen!
If the toilet bowl fills lower than the previous waterline, the tank may not be working properly. Check that the float is moving freely and allowing the tank to refill all the way. Also make sure the filler tube is filling the toilet and is not directed elsewhere.
There are many different models but this is the one I could find closet to the $150 price range. GERBER Two Piece Elongated Toilet w/ 10" Rough-In 0021410 White, I hope that helps.
Type Sarasota, FL Gerber toilet supplies in the search engine for a list of suppliers.
Either high water pressure above 80 PSI. or a defective valv.e
Either on the underneath side of the lid or on the back of the tank inside there should be a model number. Possibly on the underneath side of the tank also.
remove and install a new filler valve and get a proper flapper for your toilet at a plumbing supply
it depends on how good the pluming is.
In a toilet tank or water reservior to regulate filling.
Hire a plumber! or you could replace the seal inside
Inside the tank on the back side there are usually numbers stamped in. If not there, under the tank may be printed on ones.