If I remember correctly you have to take the plunger out of the oil pump first then take the retaining nut off the oil pump and push it into the carb box. To remove the stop switch take off the plastic button. Since you do not have the Poulan tool you need to find a deep well socket that will fit a little shy than the outside diameter of the switch. Then gently take a mallet and tap the switch into the carb box as well. The problem with the old style pistons was that Poulan forgot to ping the retaining pin in place on a limited run. You may be able to find a drill bit that will fit into the retaining pin hole and then ping it into place. One pin holds both rings in place. You will actually loose the nice compressing you had, but the saw really was not designed to be a high compression engine, but an engine that will run 1,500-2,000 hours.