1.6 HDI injector seal replacement

[Enigma]

Hi lads
Planning to replace set of injector seals on only 1 of 4 injectors.
Eng 1.6 hdi 110BHP (160 000km)
Would appriciate advise.
It is RH injector that is leaking badly rest are bone dry. So will only remove 1 injector. However do you recomend removal and replacement of 2 studs also?
Thanks
E

[Stewart(oily)]

I have done a few of these and have got away with replacing just the washers and seals, I lack a torque wrench that goes low enough to tighten these and resort to using my tiny ratchet and being gentle, the worst part is getting the seat clean before fitting the new copper washer, a short piece of garden bamboo with a slot in the end to hold strips of rag in the battery drill, and brake cleaner, tighten the other injectors while you are there, the last one I did they were finger tight!