In this stand, the coarse focus pinion and body tube rest in a block of brass which can also be moved up and down. This is done by means of the fine focus mechanism, is very sophisticated gear assembly that cannot be adequately described here. The focus design illustrated by this Leitz stand has one serious shortcoming, the entire weight of the body tube and coarse focus block must be borne by the surprisingly delicate fine focus mechanism. For observational purposes a well made microscope will provide decades of service using this design. Unfortunately, on poorly made scopes, or ones that have been abused, this is one of the first areas to show failure.
Repair is often difficult, or on older stands, impossible.
Always pay very close attention to the fine focus system when inspecting a used scope. There should be no rebound effect, and no drift in focus. If this is noticeable - look for another instrument. Many modern scopes have abandoned limb mounted focussing altogether. The body is secured to the top of the limb.