Photo of the wanted Vernier attached.....
It dates back to the 1950's and 1960's (the days before CNC had been invented).
I still have an Oric Green CRT and three circuit boards available (swap?).
viewtopic.php?f=13&t=5582 Orac CRT monitor, green screen
viewtopic.php?f=13&t=5581 Three Orac boards and two cables