I am trying to help my brother with a pump problem. (laid-off needs a quick fix) Water pressure started leaking down... now hardly any water pressure. Pump appears to be working fine, pumps to 50 lbs. then turn on water and pressure falls off.

You didn't mention if the water pressure gage on the pump line maintained pressure if no water is turned on or if the pump Quick Cycles on and off...

Off the bat it sounds like you have a bad check valve which it will let the pump build pressure but then that pressure is lost quickly when you open the faucet and at the same time the check valve at the pump is also letting pressure out.

To check that Run Pump and see if the pressure gage keeps dropping. If so and nothing is on in the house your check valve at the pump is not holding.

This site cover a good range of well problems to help you out since detailed info isn't the best hear. Get back if your still stuck.

Water system check valve location & purpose - private pump and well system do-it-yourself repairs (http://www.inspectapedia.com/water/CheckValves.htm)

Shut the supply to the house off and let the pump get up to 50 PSI and shut off. Does the pressure hold or does it bleed off? Back to you, Tom

Shut the supply to the house off and let the pump get up to 50 PSI and shut off. Does the pressure hold or does it bleed off? Back to you, Tom

Yes it bleeds down to about 10lbs