Just a thought here, but the last time you tightened the nipple down you may have went a little too far with it and it may have a hairline split in it and that is where the major leaking is happening this time around. This happened to me the 1st time I changed out one of my originals prior to having it replaced by Rob for the new 510... Have you done any leak tests with the delrin cover off? That would give you an idea as to where it might be.
yup that is what happened to mine also. went too far with the nipple...well hubby did. Rob fixed her right up.
Tracey