With Bailer closed, pull apart bent wire piece to remove the plastic black (or white) spacer (see note). The bailer itself will come out through the bottom of the boat by pushing down past the flange and sliding it aft. You will see a black gasket.
These gaskets are sponge rubber. The gasket is held in place by an adhesive. Using a knife, chisel or screwdriver remove the old gasket completely. If the old adhesive is still in place remove it with a solvent like lacquer thinner.
Remove the protective paper from the replacement gasket. Carefully position the gasket and push it down firmly. You may find the new gasket is much thicker than the old and doesn’t appear to fit – it should be a tight fit, this is a good thing! You can take a putty knife to gently compress the end to fit under the clip.
Replace the bailer slide in reverse order taking care not to damage or gouge the gasket.
NOTE: It is very important that the bailer is re-installed correctly – memorize the position, or snap a photo with your cell phone before you begin so that when you put it back together the bailing portion is facing the correct position (aft).