Use a small flat blade and pry the cover up. It’s a friction fit. After you’ve serviced the gears, set the cover back in place, and give it a couple light taps in the middle to re-seat it,…..I see you have the motor mount screws out, be careful, sometimes there’s selective shims packed under the motor, usually on the locator pins. Be sure these go back where they were if so equipped. That small hole in the middle, on the shaft housing, between the two motor mount screw holes, is an oiling hole for the shaft.
Pat