Sounds like the starter needs rebuilt/replaced. I’ve also had a bad battery terminal give similar symptoms.
Give that starter a sharp whack with a hammer and see if it helps.
Do not whack a starter with a hammer. Unless you’re in a spot where you’re going to drive it to the shop to replace the starter.
Pretty much all starters have the field magnets glued to the inside of the housing. Hitting it with a hammer will most often knock them loose. You may be able to lightly tap one and get away with it, but why risk it?
