Keith Monks tonearm Mk III counterweight

The instruction manual for the Keith Monks M9BA Mk III doesn't seem to correspond 100% with the arm itself.

My question: how is the eccentric counterweight adjusted for azimuth? The manual says to hold the hub of the arm with one hand and with the other to twist the counterweight gently. I tried that but it wouldn't twist but I also did not apply too much force lest I fractured something. There is a hex screw underneath the weight which, when loosened, loosens the counterweight too.

Of course it'd be much easier, when the arm tube is in place, to twist the counterweight (if such were possible) rather than to mess with a hex wrench, especially when the hex screw is located in such an awkward position.

Thank you.