Hi Ed,

Yup, I found the 641 also, the thing which is odd is that the CM10-12A
is designed for linear while the 641 is FM class, I am surprised that
they were crossed. The CM10 is supplied with a matched thermistor, and
I doubt that it will track the 641 correctly.

I have a low gain CM10 and I think that direct replacement is the only
way to go.

Thanks for looking

Regards,

Mark.