Markster,
Clean the mg surfaces with the $$ bill. Not everything is visible on the surfaces. (oil)
You can test the mg by unsoldering one of the wires and applying a voltage to it to see if it will release. 1 1/2, 3, 4.5, 6V. It shouldn't need 6V. While you have the wire off check the V to the wire.
Really want the top cover off?
Set the shutter speed to B and the ISO to the highest available.
There's a cover around the lens mount, 4screws. Two screws under that.
Rewind knob, c clip holding the plastic cover on.
Wind side...Wind lever, spring washer and plastic washer, spanner nut, shutter speed dial. Be careful with the ss dial, there's a peg on the bottom that holds a spring loaded dial beneath it.. if it's allowed to snap it may break the tungsten wire that connects to the ISO resistor on the wind side of the camera. Lift top off. Gently.
On reassembly, the ss speed dial need to engage the notch on the lower dial. Engage it and turn it CCW. It will drop into place. The it's just a matter of putting screws back in.