How Do I Set the Zoom Magnification Range on a Leica Wild M10 Stereo Microscope?

[Atariwarrior]

I was very lucky to find a Leica Wild M10 stereo zoom microscope on EBay for home use after looking for almost a year. I'm having a problem setting the range of zoom magnification settings.
There is a window next to both zoom knobs showing the zoom magnifications settings: 8, 16, 20, 25, 32, 40, 50, 63, 80, 100, 2.5, 125, 3.2, 160, 4, 200, 5, 250, 6.3 . The previous owner has set the click stops to start at 20 and end at 2.5. I can go no lower than 20 and cannot go beyond the 2.5 setting.
I use an M10 at work and it has a similar scale but different zoom increments: 8, 10, 12.5, 16, 20, 25, 32, 40, 50, 63, 80, 100, 2.5, and 125 (appears to go higher but view is limited by the window). The click stops start at 8 and end at 80. I cannot go beyond 80.
On my personal M10, how can I set the range of useable zoom magnification settings? I would like to start at 8 and go up to 160X if this is possible. Or is this magnification setting limited to the particular version of M10 that I have which is apparently different than the one that I use at work?
The manual says: “Hook a finger into the back window of the magnification changer and displace the scale so that the number 16 is opposite to the index.” The example was for setting the zoom magnifications for 16x to 160x.
I tried this and the window and scale would not move at all.

I'd appreciate any tips if anyone knows what to do?

Thanks.

[75RR]

Don't have an M10 and have not used one so my suggestion is more general in nature - can you find a way to measure the magnification and therefore compare what you are seeing with what the dial says?
Perhaps photographing the same object at work and at home (using a cell phone) will work. That might clarify the problem.

At the same time you may want to check what combination of objective/auxiluary lens/eyepieces it has.

You may also want to ask your question at the Wild forum: https://groups.yahoo.com/neo/groups/Wild_M20/info