Hello Terry,
Well, I went ahead and did it, this morning.
First I tried resetting using the MRC 'universal' factory reset procedure- "9,9". No success.
Second I used the three CVs. Second try I got this: "CV49 = 1 - 128; CV50 = 2 - 255"; CV56 no verbal, but "got 3 toots".
Tried F10 did not...