Replace a bathtub overflow gasket with the part and orientation specified for the drain assembly, while supporting the hidden overflow fitting. Confirm access for inspecting and leak-testing the repair before removing the cover. Gasket shapes and fastening methods differ. Caulking over the opening or overtightening screws does not repair a failed hidden seal.
Confirm that the overflow is the leaking part
A leak that appears when water reaches the overflow is a reason to investigate that seal and its connected pipe. It does not prove the gasket is the only failed part. A bathtub leaking through the ceiling below separates overflow symptoms from the bottom drain, supply and shower-wall leaks.
Stop using the tub once a leak is evident. Do not keep filling it to reproduce damage in a ceiling you cannot inspect. If water is near a light or electrical equipment, follow what to do about a ceiling water leak before working on the drain.
Match the gasket and fastening design
Overflow systems use different gasket shapes and mounting arrangements. Kohler's cited bath-drain manual specifies a tapered gasket with its thin edge at the top for the covered assembly. Oatey's True Blue installation guide instead describes a preassembled overflow gasket and a threaded overflow lock nut. Those examples show why one orientation or screw-tightening recipe cannot fit every bath.
Use the diagram for your drain and replace damaged or incompatible parts. A bead of caulk over the overflow opening changes its intended function and does not restore the hidden gasket joint. Do not close the opening to let the bath hold more water.
Provide access before loosening the cover
The hidden overflow fitting can shift when its fasteners are removed. Kohler's retrofit guide specifically calls for access to the back of the bath because removing the cover can affect the seal. An existing access panel may provide that view; other installations need a planned opening or a different repair approach.
Support the fitting as the applicable instructions require, seat the new gasket without folds or misalignment, and use the specified fastening method. Do not tighten harder to compensate for a wrong gasket or damaged fitting. If the assembly cannot be held or inspected, a plumber should establish the access and repair method.
Check the repaired connection
The repair is complete only after the actual overflow connection has been inspected under the manufacturer's leak-test conditions. Oatey's guidance calls for inspecting connection points behind the tub. Stop immediately if water escapes. Removing a bathtub drain covers the separate bottom flange; changing that flange will not fix a failed upper gasket.