Q: Having a starter issue and I have done all the troubleshooting to know it's the starter. 1997 Ford F150

Trying to start the truck I get a click! I checked at the firewall battery fuse panel and then at the firewall starter/ignition solenoid and then at the starter itself ! I'm getting power to all those points. The battery is putting out 14 volts. I've arc started it several times at the starter solenoid. I tried having someone sit in the truck and turn the key to the cranking position while it tap the starter but I found out that didn't work but what does work is instead of tapping the starter , all I have to do is touch the front plate with a metal rod and it fires right up! There's a little bolt that is slightly lose but I can't seem to tighten it on the front of the starter but as soon as there is contact on the front plate, it fires right up! I don't know if I need to replace the starter or what! I've never heard of this happening and It's not jammed or anything so I was wondering if you knew what to do about this? Thank you

My car has 298000 miles.
My car has an automatic transmission.