Hello, Nautilus users! Questions

[Digging Fool]

I've been digging for 35 years, but just got my first nautilus today. It's a DMC II(no suffixes, just plain DMC II). There is a toggle switch on the front of the box(near coil connector plug), and it just says on/off. I have no idea what that one is for. I know what the other 2 are for. No manual came with the machine, and I can't find any download instructions for it. Should be a fairly simple machine, as it only has 5 knobs and 3 toggles. Seems to work ok, and it has 4 9-volt batteries. Any tips would be appreciated.....Thanks!

[Digging Fool]

I think the Nauty users have all died.....

[TimC (North Alabama)]

I have the IIB model, on it, it is the auto tune switch.

[Digging Fool]

I have the IIB model, on it, it is the auto tune switch.

Thanks! Got my owner's manual from Nautilus today, but just got home from work(late). I don't know what distinguishes the II from the IIb and IIba. I have some learning to do, but like the machine.