if that little o-ring slipped out at all and got pinched then thats the problem. I like to coat it in grese so that it sticks in its groove when i put it together. It may be the seal though
. If theres a groove in the crank pulley from where the seal was riding you can sand the seal down so that when you bottom it out in the pump it rides in a different spot on the crank...pulley.
