I changed the o ring and the copper washer but took out the whole assembly. The cylindrical part at the base was removed, cleaned and reassembled. What orientation does the cylinder go in? It has some holes in it I saw and I thought it turned freely. I'll try the white lithium grease on the parts next time to reassemble it. I removed #'s 98, 95, 101, 104 and 122 from the delivery valve on the above thumbnail diagram.
Thanks for your help
steve