My BHS came with a rubber cap to fit the fine adjustment knob "increases the sensitivity of the fine focus motion" (optionally available for the BHS).
Looks similar to your nylon one, slightly tapered 'hole'.

Zerene does an incredible job to correct for this. I have had specimens in water that moved considerably between frames.

By checking "Align each frame against first frame separately" in Preferences, all frames line up.

Your image does seem to be less sharp than I would expect from that lens. I just happened to be photographing a bug head with the same objective, Nikon D7200, 98 frames @ 0.006 mm. 2 diffused flashes, Zerene PMax. Original frames were RAW and processed in Adobe RAW and saved as .tif Small image is t...

That's a BHS, a superb scope; I have the same. You need an Olympus NFK projection eyepiece, preferably a 2.5x. Simplest way, and cheapest, is to support the camera (no lens) at 150 mm (I believe that is the correct distance) above the NFK. I have a wooden frame that holds my Nikon DSLR. A cardboard ...

As you likely know, they are tiny. They were collected a few days ago in a Berlese Funnel sample along with quite a few large hairy elongate species. Weather here is cool to cold and obvious wildlife is absent. So, collected some old leaves in odd corners of the garden and ran them through the funne...

Yes, they belong to the 4th Oder in the following classification:

Class Collembola - Springtails and allies

Order Poduromorpha
Order Entomobryomorpha - Elongate-bodied Springtails
Order Neelipleona
Order Symphypleona - Globular Springtails

If not, then what ?
Nikon D7200 CFN 10x finite, Zerene stack

What - no prize for correctly guessing!
How about Scorpions of the Pseudo type?

The only blades my pharmacy had were Wilkinson Sword, made in Germany. I bought a pack, of 10, $14.00 !!
These are the ones I used.
Still waiting for my stains, from the UK.

In this month's Micscape Magazine there is an interesting technique: http://www.microscopy-uk.org.uk/mag/indexmag.html I have tried to hand cut sections using several methods, none worked! This method works at almost no cost. Here is a section of a Hydrangea flower stem. I have only zoological stain...

I still have the 13 images that made this final image; any use?

Possibly irrelevant!
I have an Olympus BH2/BHS with DIC; very simple setup, explained in the Oly brochure.
Images likely not as good as more modern DIC's but may be worth the hassle your having
Old image here; scroll down:
http://www.photomacrography.net/forum/v ... 14&t=12995

Love it !

This one and your sunflower X-section are nice images. However, they would be more interesting if there was some interpretation of the various morphological parts. I guess what I am saying is that "art" is good but I would prefer "science"; why not both ?