FOCUS RACK TENSION ADJUSTMENT KNOB
This picture shows the “tension adjustment knob” on the underside of the focuser, which pushes the rack gear harder into the pinion gear.
If it is tightened too much then it could make the focuser difficult to rack and in and out, but it is not intended as a “lock”.
There is no lock as such, because it’s a safety feature, as if the focuser is locked or obstructed and one then then turns the fine focuser, it will destroy the mechanism.
FOCUS ROTATION TENSION ADJUSTMENT KNOB
This shows the focus “Rotation” tension adjutment knob.
These are also not locks, they are for rotating the focuser entire, and adjusting the tension at which the focuser rotates. The main adjutment knob acts as a brake and secures the rotator in place.
The 3x brass Teflon tipped screws each side are the tension adjustment screws. These can be gently tightened up with the correct size flat head screwdriver so that the focuser can only just be rotated with a little effort when the top screw is loose.
The top adjustment knob is then used to secure that rotation angle so that it cannot change during imaging or the creation of flats, or when a diagonal used leaning to one side, etc.