Window replacement

The window that bumps out over the garage, which is in the master bedroom, is leaking like crazy. Thought it was plugged last year, but no. We've noticed on the exterior of the window that there is an area about the size of a 50 cent piece of the window trim - not the wood- is missing.
Thus water drips through there, down the inside of the blind and to the sill. I pulled the blind up and water leaked down from it's edge and there was a puddle the size of 2 TV remotes nose to nose on the sill.

I don't know if this can be plugged or if the window has to be replaced. Been happening for about 3-4 years now, when rain slants toward the house.

Any ideas?