K4040 led 12 lit all the time

Does anyone know why led 12 is lit all the time, including during power up? The pcb at the time does not have any transformers connected, nor any valves plugged in! LM3914 i.c was replaced but to no avail. I did note elsewhere in this forum someone had the same problem, but didnt get a reply other then ‘check the negitive bias’. This couldn’t be the cause because there is no connection with the dip switches off and no valves in circuit?

This is normal, led 12 is always lit.