[Arran]

Hi guys,

Thanks for the replies.

There are no rubber grommets. The cap's rotor is electrically connected to the housing and through it to the Chassis GND.

For short, before I got all these replies I took the cap apart (easy), and washed it in the dishwasher. I had some reservations, but it came out good. I decided not to buff anything: I need it clean (it is now), but not necessarily glittering.

The cap is easily and logically disassembles and re-assembles; it's a snap to both take the rotor out and to put it back, so no scare here. The two steel springs that control the rotor's location are unique and fit only one way, so no problem with remembering which one's where.

To take the cap out is 5 wires (3 wires to the stator and 2 to the light bulb) and 4 screws - three hex screws and the one long screw holding the scale mechanism.

Now I need to buy one 71A tube (one out of two has no filament continuity) and connect Hammond Xformer to the speaker.

Wish me luck

Before you spring for a new 71A try resoldering the filament pins, some of those older tubes have bad solder joints by now.
Regards
Arran