I need a key for pay phone.

24/1 is the correct ratio. I certainly wouldn't go 50/1 but you could split the difference with a good synthetic.

1957 Johnson Seahorse QD18 10hp Oil Mixture - Marine ...

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Yes from any online source.

Please specify the make and model of the calculator. There so many make and model of the calculators in the market place. If you just need a general of how to used a calculator , then it's easy. Most calculators is the same basic. There is a plus key, minus, equation, division, M+, M-, MR, If you really want any manual please phone 780-424-1957

Try the help tab on the company's website http://www.retroshowroom.com/IVG2/N/ProductID-64503.htm

The company has a website and a question tab http://www.retroshowroom.com/IVG2/N/ProductID-64503.htm

I recommend that you google directory card for Lucent AT&T 1872 phone. This should take you straight to what you need. You may have to pay a price for it but at least you will have what you need.

when receiving call, can't hardly hear person calling in., sounds as if they are miles from their phone talking

Try the company website. There's a help tab. http://www.retroshowroom.com/IVG2/N/ProductID-64503.htm