The mirror box mechanism has undergone several updates and mofications over the years.

There is no real need to remove the top cover in advance.

In early samples, the mirror charging mechanism is quite different.

On early Spotmatics, the frame counter plate mounting screw has a right-hand thread. Underneath is a clock spring that pops off and must be rewound when reassembling. On later Spotmatics, the frame counter plate mounting screw has a left-hand thread.

On early Spotmatics, the topcover mounting screw near the frame counter is on the right side of the topcover. On later models, it is under the frame counter.