Try moving the primary cover around with the screws loosened up. You can do that without loosing any fluid. Just loosen each screw about one turn then tap on the cover with a soft faced mallet. Get the screws just loose enough until the cover moves. Move the cover up, down, left and right while trying the starter. When the pinion gear engages the ring gear tighten the screws back up. This method works sometimes, I've done it !
Disclaimer : Don't believe anything I say unless you are absolutely sure that I know what I'm talking about .