Anyway, I have a few volume controls which need to be cleaned, is there
anything over-the-counter which would do the job?

Tuner cleaner - hard to find now
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For this purpose I normally use 'Contact Cleaner' which is non-chlorinated.

A supplier here in the UK is : Maplin who has stores in many cities and
towns in the UK ,even in Scotland .

Frank GM0CSZ / KN6WH