[Arran]

You can also run one of these sets by putting 6.3 volts AC directly into the primary of the vibrator transformer, but you would need to replace the synchronous section of the vibrator with a pair of silicon diodes. However the tube filaments will require clean DC as they are battery tubes, otherwise the set will either not work or hum at least. I don't know if you can do this for the long term or not as the vibrator transformer is designed to operate at around 110 cps not 60 cps, maybe they can take the abuse since vibrators, by the nature of the contacts opening and closing, produce a voltage spike.
Supposedly you can clean a vibrator by connecting a 40 watt light bulb in series with it and running it off the AC mains, I have not tried this however. I would go with a solid state substitute, either bought or home brewed, then as long as the hash capacitor is in good order it should run reliably for years.
Regards
Arran