Starting problem

When turning the key to start my RZR you can hear the motor attempt to start and then it sounds like it bogs down and stops cranking. The positive terminal at the battery starts glowing orange. Replaced the starter several years ago with a SATV one. Pulled it back out and it spins freely. Gear that starter engages also spins freely. Sprayed bunch of lube in the hole let it set and stuck starter back in and still doing same thing. Whats going on in there? Is it time to pull the motor???