Pressure dropping on gauge

Hi , Im new to this form and i have a problem with my pressure tank i think. the brand name is rapidayton and i usually have about 40psi or more on the gage when no water is running. today the gage reads about 10 psi. How do i check the bladder and air pressure and determine if i need a replacement tank.
help please.

Rapidayton is a pump not a tank. They are not made anymore, so that tells me how old this pump is.

Before doing anything hasty, you might want to replace the gauge. They are usually not very high quality and do go bad quite often.

If you still have water and the pressure seems ok, it's probably just the gauge.

bob...

today i checked to see if my water level was low by running a hose. it had a steady stream for 10 mins. or so but no pressure, the same in the house.this rapidayton tank i have had for at least 20yrs. and i put air in at the vavle and the pressue rose ,then i turned the water on and water came out good until pressure dropped onthe gage

This is not a bladder tank. Putting air in the tank would increase pressure.

Are you saying that the pump never turns off because it can't make pressure enough to do so? In other words, does it just stay on 10 lbs and keep running?

bob...