Prototype set is here

[miniman82]

Quick question: this chassis has a control labeled 'Horiz Phase'. Anyone have any idea what the purpose of this control might be? It's a pot connected at one end to the cathode of the horiz output tube which sits at around 25 VDC, other end appears to go to pin 5 (grid) of the 6BQ6 (pulse reg?). Wiper is connected to the cathode circuit of a 12AT7 tube, which I'm assuming has to do with HV regulation since it takes an error voltage from an external winding on the horizontal output transformer, and also has a connection through a plate cap to the grid of the 6BQ6.