Hi Don,
if I could post scans on the BB at this time I would put up this article as it lists the current, at the time, inj. pumps that have the groove for the seal and 4F6921 is on the list.
Yes, the seal was added to remedy moisture ingress thru that area.

When we can add attachments again I will put up the PB article. May not happen until after the silly season when the IT people get back to work and find/fix the problem.
Cheers,
Eddie B.