my 2cents. I have encountered twice (both BB's) a worn starter nose cone where the silinoid pushes the gear when engaged. if not checked properly this can come from a rebuilder. The first time my car kept turning over after the key was off and removed becuse the gear went PAST the flywheel and got stuck.
I had another just grind , but had a worn cone. but you have a new (?) starter. if it has to come out again check it out. good luck.