Did you check the TEM mode of the current tube? Sometimes that identifies the tube as a problem. If it’s not in TEM00 mode, it will never work properly.
The way these work is by increasing the voltage on the tube anode until the tube starts conducting, this is usually referred to as trigger voltage, and indicates minimum voltage to cause the tube to start to lase.
Things to keep in mind about a new lps… I believe these are 100W lps.
