It's not to bad of a job. I usually take and center punch the servo housing and the pump housing to have reference marks and then count the turns comming off and then back on. New o-rings are going to turn alot harder than the old ones so use plenty of lube. One the other hand if you have to change the pump i would look real hard at changing both pump and motor. If they have alot of hours on them, one new one and one old one may not be a good idea. May cause you problems in the long run. Hope this may help.