Disturbing image movement: When focusing up and down looking at a slide the image shifts from side to side or up and down.
One possible solution for image shift is to make sure the lamp filament is centered in the field of view on the microscopes lowest magnification after the frosted filters are removed from the light path. If the filament image is off center recenter and retest.
The stage may not be perpendicular to the objective. A simple test is to stand back from the microscope and look to see if the stage is not
perpendicular. The stage has mounting screws on the focus block - these can be loosened and the stage adjusted back to being perpendicular
to the objective or parallel to the first lens or the case on the 40x objective.
Make sue the condenser is perpendicular to the objective- also if there is a swing in lens- make sure it is not half way in.
If the problem is still there you need to send it in for repair.