If the trip lever on your bathtub has stopped working or if water slowly leaks down the drain when the tub is full, repairing or replacing the linkage and plunger behind the trip lever may solve the problem.
Step 1: Remove the two screws from the trip lever faceplate to free the faceplate from the overflow tube.
Step 2: Gently pull the face plate away from the tub. If the linkage is still attached to the backside of the face plate, the linkage and plunger should pull up and out of the overflow tube without too much difficulty.
Step 3: If the linkage has broken away from the trip lever, set the face plate aside. Use a claw-type extension tool or a wire with a small hook at the end to fish the linkage and plunger out from inside the overflow tube.
Step 4: Clean the plunger and linkage with steel wool and a de-liming cleaner such as CLR or vinegar. If the plunger looks worn or the linkage is broken, replace the entire mechanism with a new assembly.
Step 5: Replace the old overflow gasket with a new one.
The overflow gasket is located between the back of the bathtub and the front of the overflow tube. Scrape away all remnants of the old gasket before installing the new gasket. Position the new gasket on the front of the overflow tube, with the thicker portion of the gasket toward the bottom to compensate for the slope of the tub wall.
Step 6: Attach the plunger to the linkage and attach the linkage to the trip lever. The linkage is typically attached to the trip lever with a small cotter pin. Slip the pin through the back of the trip lever and bend one or both of its sides up to hold the linkage in place.
Step 7: Adjust the length of the assembly by turning the threaded rod at the top of the linkage.
Step 8: Feed the plunger and the linkage assembly down into the overflow tube and press the faceplate into place.
Step 9: Raise and lower the trip lever to test the functionality.
Step 10: Fill the bathtub with enough water to test the seal of the plunger. Adjust the plunger height until a proper seal is achieved.
Step 11: Insert and tighten the faceplate screws to complete the job.