Hey Swic,
OK good for you! I hope you were very careful while you were around the back of the CRT neck. There are many nasty voltages there.
In the old days when we'd do that to monitors at the TV station, we'd use a mirror so we could see what was happening.
BTW usually those "adjustment yokes" actually purity and convergence adjustments are marked as Sam notes:
http://www.repairfaq.org/sam/tvfaq.htm
"The position and orientation of the yoke (including pitch and yaw) and magnet assembly (purity and static convergence rings, if used) are critical. Use paint or White-Out(tm) to put a stripe across all of the magnet rings so you will know their exact positions should they accidentally shift later. If there are rubber wedges between the yoke and the funnel of the tube, assure that they are secure. Tape them to be doubly sure as adhesive on old tape dries up with age and heat and becomes useless. This will avoid the need for unecessary dynamic convergence adjustments after reassembly."
Some of them will also have a nut that locks those adjustments in place but as Sam says did you see the painted stripe?
mine were pretty easy to move around.
See that shouldn't be the case.
Richard