Tank Problems?

I have a ten yr old champion pressure tank and a 135' well. When running water, in the last couple of weeks the water seems to surge, check the guage at the tank and it bounces between 25lb and 42 lbs every few seconds. I assume this is not normal and is going to burn up the well motor. I dont even know where to start. Do I need a new pressure tank or just a switch. I am pretty handy althought not an expert. Thanks

First thing to do is to check the air pressure in the tank with a tire gauge. (If water blows out the air valve, the bladder is shot and you need to replace the tank.)
The tank air pressure (with the pump off and the water pressure drained completely down) should be two psi below your pump cut-on pressure.
Bleed it down if necessary, or pump it up with a bicycle pump or portable air tank or compressor.
If it doesn't hold the pressure after pumping up to cut-off, replace the tank.
Good Luck!
Mike