[Amps] Knob interior aluminum wafer 1.75" needed

[Gary Smith]

I have a knob which is missing the spun aluminum wafer adornment 
which goes inside. The wafer is 1 3/4" & probably 1/16" thick and it 
fits into a Nye Viking MB-V-A tuner. 

Suggestions where I might look to find the wafer (or two if I end up 
needing to match them?) 

Thanks 

Gary 
ka1j