SMALL amounts of soap and water and a toothbrush - afterwards, 2 or 3 hours in the sun

I would use a soft wire brush on the laminations.

Let me clarify what I mean:

I would take a wire brush to the OUTSIDE, STEEL laminations ONLY

Then I would use a toothbrush and warm soapy water to clean the paper and windings

Then I would leave it to dry for a day or so in the sun

Then I would give it a coat of clear lacquer.