How to Fix a Cracked Primer Bulb on a Lawn Mower

Press in on the plastic tabs on either side of the primer bulb retainer. You may have to use a small screwdriver to initially depress the tabs. Squeeze the tabs in while pulling the bulb retainer away from the engine. Remove the cracked bulb from the plastic retainer. Set the retainer aside for re-use.

Remove the small round primer seat from the bore with the right-angle scribe, or any small stiff hook, such as a crochet hook. A small ball and spring may fall out of the primer seat bore. Clean the ball and spring by rolling them on a paper towel, if necessary. Avoid deforming the spring by setting it out of the way.

Place the spring and ball back into the bore in order, spring first. Press the new primer seat into the bore, with the groove facing towards you. Ensure the primer seat fully "seats" in the bore.

Install the new rubber primer bulb into the plastic retainer. Align the retainer tabs with the corresponding slots, and push the retainer in until the tabs lock into the slots.