I'm going to have to agree with pennycandy. I'm fairly certain that you can use the single controller plug from the 301 on the 400 series machines. There was a
301-1 that had two plugs like your 400 machines, but the 301-2 only has the single cord plug. So in order to use the controller from 400 machines, one would need to unwire it from the plug wire and rewire to the 301 plug wire.
Janey - Neat people never make the exciting discoveries I do.
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