Help calibrating rangefinder on Walz Envoy 35
I recently acquired a Walz Envoy 35. After a couple of test rolls, I am satisfied that the rangefinder is off just a skosh. I've also used a tape measurer to confirm. It's not far off, but enough to keep images from being sharp. I'm wondering if anybody can help me understand how to remove the top. I think I know which screw needs to be turned to adjust the rangefinder if I can get the top off.
Alternatively, does anybody know a repairperson who is familiar with these cameras?
Any help is appreciated.