Speedometer is driving me crazy- Something is Wrong

I have had to change spedo gears several times along the way. I bought most of my gears from WWW.Speedometer Gear. Store from Kerry Conklin. The price is not bad and very fast shipping. Some of the gears i have from years gone by are not what they claim they are. In the circle of the gear is the number of teeth the gear should have and it is also color coded for fast id. But they are NOT all correct so after you put in the 40 tooth gear with no change with your needle reading. It might be that your gear is marked wrong. Count the teeth Just to be sure it is a 40. If it is i guess you can try the higher numbered gears you have said are on order. Should you need to buy more down the line , check out the gear store's price on them , maybe you could save a buck or two ?