I have a 4430 sprayer and today my product pump started leaking.  I had the dealer rebuild it but I'd like to get a spare.  Dealer cost is $1,400 and I can get one online for a few hundred less.  There are several models of the 9306 (HM1C, HM3C, HM5C, HM5C-B, HM5C-3U).  Which one do I want?