Do you mean the tank is waterlogged?

I looked up the Ruth Berry system. It uses a tank like the old galvanized tanks. It has a valve about 2/3 of the way up the tank which is supposed to release excess air. What I could not find out is how does the jet pump get air into the tank. Conventional systems of this kind use the pump to inject a charge of air into the tank each time the pump cuts on, and the valve mentioned above makes sure the tank doesn't simply fill with air. So if you are saying your tank is waterlogged (no air charge), then the method for adding air would seem to be the culprit.

In looking around on the web, I came across these folks. If they sell parts, I'll bet they can troubleshoot by phone.

Law Supply - Ruth/Berry Pump Parts