How to tighten/re-secure oven-door handle, Tricity Bendix President SB431?

The door-handle for the oven is secured by screws from inside the door, but the screws are concealed behind the inner-door. There is a very narrow gap between the inner and outer door panels, but the thinnest cranked screw-driver I can get is still too fat to go thro' this gap to tighten/re-secure without separating the inner/outer panels. Am reluctant to do this separation, just in case it causes a complication in trying to put these two bits back together.
First question is, is the inner/outer panel separation the way to do it AND that it is easy/simple to put back together?
Second question is, how otherwise can the door-handle be re-secured & what special tool may be required?