Help. I have been battling with this situation for almost a half year.

I installed a new 3/4 hp, 2 wire, 230v deep well pump last December. The unit had some issues with low flow at first but after turning it off and on a few times I had no problems.

About 6 months ago I shocked my well with H2O2 and shortly thereafter I started having pressure problems. The pump would violently start, almost seems like water hammer, and then just hum along. I would get a burst of water pressure up to 30 psi and then it would just taper off quickly to below 10 psi. Flow is just a trickle. If I keep everything off in the house it gradually builds to 60 psi. Pump turns on back again at 40 psi but same problem.

I even replaced the pump and put new wire and a new breaker in the box.
Same thing.
Specs: Well is 160 feet deep, Pump is at 140 feet deep. Water level is 2 foot from top of casing now. One check valve is in place at 40 foot down (could it be the check valve? I replaced this just 2 years ago). Torque arrestor is in place. Pressure tank has new bladder with pressure at 38psi.
Continuity shows from each leg of pumpwire to ground. But I am getting continuity from leg to leg.
Voltage is 115v on each leg to ground.

Is this electrical? Is this the check valve?