why could the switch catch while starting it up?

What is your question?

when we start it up sometimes it will start good.. then some days it will start and the starter stays kicked in it wont kick out. when it wont kick out we have to pull the battery cable off and hit the cetonoid on the fenderwall in order to stop the starter from catching what could be causing this and we have also put in a new altenator, and put in a new starter..