Falcon Super Action Candid - focus stuck

A while back I acquired a Falcon Super Action Candid 127 half frame camera, at least I think that's the model. It is one of the better Falcons with several shutter speeds up to 1/200s.

I am aware there is a button to press to unlock the focus. Whatever I do, the focus ring is stuck. Does anyone have any tips to free it up? I do not fancy squirting WD40 or any similar sillyness...but perhaps something can ease it?

Here's the manual, hope it helps
http://www.cameramanuals.org/pdf_files/falcon_candid_camera.pdf

And here, Mike Eckman says the "Falcon Super-Action Candid has a focus lock that must be pressed in while rotating the focus ring" in a great write up on the little camera
https://www.mikeeckman.com/2019/07/falcon-super-action-candid-1938/

Unfortunately I was already aware of the focus lock and it's not made any difference.