Pump wont shut off. Has new pressure switch. Checked pressure tank and tank pressure good. Backflow to 0psi within seconds of shutting power off to pump. Pump only gets up to 48psi while continually running. Bad check valve cause both issues? Or cracked line? Also when shutting off power to pump I can see the water movement way down at water level inside well casing so I'm sure its backflowing at the bottom.