On our Arrow 750, I am only getting 40 volts to the plug that goes into the power supply on the control - should be 240 volts. Any ideas?

You have to check the origin of the 240v, if you have a modern sensitive VOM, then often leakage/capacitive coupling can give you a AC reading, but due to the fact it is leakage, it will not support any kind of current.
If this is so, you may simply have a fuse O.C.
Al.

I've been trying to track it down as best I can. I guess I'll just keep at it.

Actuall one side of the plug is at 120v, and the other side only has 6v and when I test them together I get 40v

Actuall one side of the plug is at 120v, and the other side only has 6v and when I test them together I get 40v

With respect to what? Ground or neutral?.
If so you have a blown fuse on one leg.
Al.

To machine ground.

I've looked through the electrical schematics and i've traced it back to a "45 Second Switch" but I can't seem to find this so-called switch. It's not like we've ever had to wait 45 seconds for the power to come on before.

I had Cinci tech support on the phone today, but it was the end of the day and I'll have to call back on Monday. I thought I'd get some ideas here and play with it some more on the weekend. I've sure learned how to use a multi-meter anyway! And I haven't even zapped myself yet :)