[PJL]

OSRAM and MARCONI are the same vales just different labels. OSRAM was used for commercial sales, MARCONI for the professional market.

The lamp limiter will glow bright due to the high quiescent current of the amplifier.

If you are planning on using this regularly and want it to be reliable and as good as it can be, I would replace all paper capacitors and replace any resistor that is out of tolerance. You might be able to reform the electrolytics but I would want to check their ESR and leakage current at normal working temperature before using the amp.

On powering up without the lamp limiter, you should monitor the PX4 anode current (by measuring across the cathode resistors) to check they are are not taking excessive current and are reasonably well matched. The valves may need a little time for the gettering to absorb the small amount of air that may have leaked in during storage.