new lpop no oil pressure P.O. cust

[fleet1]

customer brought unit in with no-start, ran diagnostics and found no oil pressure coming from lpop, pulled unit found housing and gear tore up, replaced and still had no oil pressure (testing at oil filter inlet) removed filter housing to see if we had direct flow - none, this was a poorly maintained wrecker, suspect suction tube restriction or sucking air, did not tilt to try that after install. anyhow, pulled oil pan and found metalflake in bottom, also some needle bearings,and piesces of needle bearing, no rod or main bearing material,customer wanted it put backtogether without regard to where the needle bearings came from. customer pulled unit, long story short, after lpop gearotor and cover replacement, should have at least some oil pressure, found o'ring on tube ok but was not able put together and test,customer pulled unit as-is.Ford said needle bearings probably came from a rocker arm.Anyhow, why didn't we have oil pressure after cover and pump replacement?