Hmmmm, "Clear Pattern"?
The best that it can do isn't all that clear.
Not sure you'll ever track this info down. Don't think he sold all that many.
If any of the three main controls, for brightness, focus and astigmatism acts like it's not being turned at all, that control may be bad. Can't remember if the focus knob is on the outside. Pretty sure the astigmatism (second focus control) is a screw-slot style large trimmer control on the inside.
Fixed resistors, usually 1 or 2 Watt are wired to those controls, to make variable voltage dividers. Those variable voltages set the size and brightness of the dot on the screen. When they're working right, at least. Bear in mind these parts run at a thousand Volts, more or less, and can knock you for a loop even after the power is removed, from juice stored in capacitors.
The fixed resistors that feed those controls will also fail, or the resistance value may change radically from what the color-code markings say.
Since that unit is 30 years old or more, failed filter capacitors in the power supply are possible. Any electrolytic capacitor that is original can no longer be trusted after this many years.
73