Swapping injectors around is a time consuming exercise , by far the quickest is to get the ECU codes read & this will point you in the right direction . Common rail engines are not like earlier style diesels , you could search the link & see if there is a member close by who can read the ecu for you
http://www.zeemaps.com/map?group=280351
I strongly advise against opening up the fuel system , unless you are familiar with common rail systems , mainly due to the very high pressures present in the fuel rail .