If you have a particularly stubborn dowel pin you’re trying to remove, you can add a dab of lapping compound then use your dowel pin puller to extract it. A compound is needed with which to abrade the valve seat surface so it will precisely mate with the valve seat. Without it a Valve Lapping Tool is useless.
Goodson offers the industry standard Valve Lapping Compound, often called “Clover.” This compound is silicon-carbide abrasive granules in a petroleum-based suspension. It is available in several grits from 120 Grit all the way up to 1200 Grit. You can purchase it in 2 oz. and 1 lb. containers.