I bought a used, early 1845c. PIN number is JAF0042XXX. I am hoping to service it. In the manual I notice that the HTO additive for the hydraulics is not needed for PIN numbers prior to JAF0067438. I don't know the history of this machine and what has/has not been replaced. Should I just skip the HTO additive, or should I add some just in case something was changed out along the way? What would you do? Thanks.