Jeff, ZL3TNV wrote:

I need a concentric knob pair for an Eddystone 990R - the original light
grey type with brushed aluminium end insert.

The main source of Eddystone spares (and service manuals) in the UK is:

Dave Simmons,
Windana House,
North Aston,
Bicester,
Oxon, OX25 6HX.
Phone/fax: UK: 01869 347 504

There is an Eddystone User Group (of which I'm a member), which publishes an
excellent bi monthly newsletter of more than 40 A4 pages of technical info
and advice, nostalgia, ads, etc.
The Secretary of the Group is Graeme Wormald, G3GGL, who can be contacted
at:

Hope that helps.

73,

David.
G4EBT.