The later Parker Hale 5C's with the squared knobs are rather shoddy compared to the AJ Parker Twin Zeroes, and particulary the Centrals; sloppy fitting, backlash etc. PH even used an aluminum body on the late ones, which is particularly cheap 'n nasty.
Which of course is why serious shooters used Centrals and no one bothered with the PH's anymore. Even the TZ has backlash in the windage mechanism. "Good enough" as long as there's no competition in the marketplace...
A bit of 600 grit wet 'n dry paper rubbed in a straight line will clean up the scales nicely.
I have heard a few people complain about the sloppy fitting, backlash etc on the PH. I sure don't see it the example I have. Tight as a drum, even with the locking screw loose there is no movement.