Starting a few months ago my 40 gallon domestic tank relief valve leaks once in a while to relieve pressure. Today I tried to check the pressure in the expansion tank, and read no pressure. I tried to add pressure to the expansion tank after shutting off the water and opening a faucet, but it was almost impossible. I could add a small amount at a time using my compressor. Compressor gauge would spike up and then over a few minutes slowly fall. It appears that I was successful adding pressure because a few hours later there was a lot more water on the floor. But I also cannot relieve pressure when I push in the needle on the Schrader valve. It’s almost like the Schrader valve has rusted almost totally shut inside the tank. The needle does move when I push it. Seems like I may need another tank if that’s what is happening. Thanks for any thoughts you may have.