[Jaydee]

Hitting the solenoid could unstick it. If the solenoid is stuck because of corrosion or grease build up. A new starter shouldn't have that problem. It is unusual to get stuck like yours. I have seen it once and the starter was glowing red and the battery almost melted, because they didn't disconnect it. Sometimes the solenoid return spring breaks due to rust. Glad that you have a cutout switch.
JD