Freeing the fine focus and replacing the course focus tension knob on the Zenith Biolam

The fine focus on my Zenith Biolam developed backlash due to inadequate
lubrication of the fine focus sliding plate. This 7mm plate is situated
between the fixed block holding the stage and the moving limb housing
the coarse focus controls. See
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul04/iwlomo.html
for illustrations. First remove the thrust plate and spring from the
top of the fine focus sliding plate (Fig 3) - the part marked with a
serial number, the Lomo logo and Made in USSR or Russia. Then remove
the aluminium plate and plastic focus dial from underneath and remove
the base (Fig 4). With the course focus adjustment tensioned it should
be possible to pull the stage up and down to move the grease around on
the fine focus sliding plate. Once it is sufficiently lubricated,
reassemble ensuring that the base thrust pin (Fig 8) is located in the
bottom of the fine focus sliding plate. Also ensure that the longer
screw is correctly placed in the plastic focus dial as it acts as an
end stop against the screw in the aluminium plate.

If the course focus tension knob comes off, push a blunt instrument
into it to remove the end cap without damage. The nut can then be
reattached. Don't glue the end cap back on with anything too strong
in case it needs removing again.

.