I inherited a White Coinmaster. Can't find the manual for it. These are the following numbers; CM#3, F291, P/68. I was able to get just get some info from the CM4 manual. And that was how to check the 2 - 9V batteries & they check out perfectly in the Null position & that's it. I do get a tone & it does vary going across a few quarters but the meter doesn't budge. I've tried the dial knob through the complete range with no luck on the meter moving. Help please. PS: While I do want to get this working I'd be curious to it's current value Working or in the worst case not working.