The SZH is not without its faults.
This is the focus block for an original Olympus SZH. It moves the microscope body up and down to focus on the work surface.
The SZH is a heavy body, even by stereo scope standards. But hey, the focus block looks beefy enough--- nice big knobs, large dovetail with hardened opposed cylinder bearings, even an internal articulating spring assist to counterbalance the microscope weight.
And like every other SZH focus block I've checked, the internal gearing is completely destroyed.
Here's what's left of the brass rack gear. It looks like someone tried to mod their way around the damage and failed spectacularly:
The racks disintegrate so easily because *this* is the pinion:
All that design work to handle the weight, and they used a tiny pinion that only has at most one tooth fully engaged at a time. That's facepalm territory.
Olympus must have realized the mistake, because the pinion was greatly enlarged in the updated focus block for the SZH10. A variant of that updated design is still in use on their current scopes. But one pretty much never sees SZH10 focus blocks for sale without the rest of a microscope.
Spare racks for the original SZH block are impossible to find, and I'm not equipped to hob out a new part. But why would I want to? The design would still be failure prone. And that leads us to FrankenScoping for fun (but not profit)...