Just the result of my impatience. The elevation adjustment is actually a very robust rear-access 10mm jackscrew/wormdrive affair, you can see the screw adjustment large alloy knob to the left of the red area you outlined. Of course I had to try turning it without bothering to realise there were also two friction locking nuts , one each side, both screwed down a bit at the factory but not enough to stop a determined rotation of the adjustment knob by yours truly...I never was much of a one for RTFM first
Actually seems a bit pointless to put paint on an area that will be subject to friction, even if it's only a lock.