Have you checked to make sure the pressure line is not kinked or clogged? It might be clogged at the tank connection.

I'm going to take it all apart and check again. The cut in pressure is suppose to be 40psi. I had my tank set at 38psi, yet the pressure still goes to zero for a few seconds before the switch turns the well pump on. I even lowered the tank down to 30 psi hoping the pump would kick on before all loss of pressure....no luck. This baffles me.

All fixed- Thanks Randy. The pressure switch is thread on a little 2" copper pipe that was completely clogged. Wasted $20 on a new switch, but the education is priceless!!

I have seen that before myself... sorry about the switch, but you know that part is new now.

Thanks for posting back and saying how it was resolved.