The question I'd be asking is why is there only 20 psi in 1st. The only component applied in 1st is the rear clutch. Why does the pressure rise in all the other gear selections? The pump must supply even more volume to additional components that are applied in every other gear other than 1st. If there was an internal leak beyond the valve body 2nd and 3rd pressures should be even lower than 1st. Think on that.
Doug