not sure what you are talking about, merrit used dozen different monitors and probably even more than that in tubes. they would often get a tube/yoke set from a manufacturer and just use it with their chassis.
it could have been for a rotation control. or some other adjustment like remote focus.
if it was disconnected, I wouldn't worry too much about it. iv'e seem monitors with whole circuit boards left attached to the deflection yokes, but have nothing connected. others, tiny coils with plugs attached to nothing.
made for something at one time for someone, but ultimately unused.