1992 Ford E-Series Van Bad starter?

Yes, another post by me, about the same van.

Sometimes when I turn my ignition with a warm engine, it fails to fire up. The starter makes alot of noise, like sprockets grinding eachother.. It's the same sound you get when you try to start the engine when the engine is allready running.. I had a look at the starter, but it seems rather new to me..

I could use some help on this, because it's getting rather annoying..