Hi Graham
I just nick the top of the pintle cap with a razor and then "peel" them off, its really easy they are very thin
(I have a couple I am cleaning right now so can send you pictures with the pintle caps removed if you want) I would do all of them, they are cheap from the injector stores and they are good protection for the end of the solenoid pin. If you cannot get them cheaply let me know and I will find you some down here.
To install I have a special jig but all you really need is a piece of hardwood with a small hole in it and then just put the cap in the hole and push the injector into it. Hardwood or plastic is best as softwood tends to shed fibre and you dont want that.
the big rubber o rings can be bought at NAPA or similar and are cheap, but buy the top hat injector seals from benz its not worth messing about with cheap copies of those
I always pull the filters and unless they are solid just stick them in your ultrasonic cleaner with professional injector cleaner, if you dont have any then use something like 50% sea foam 25% mineral thinners and 25% STP total injector cleaner, techron or similar injector cleaner concentrate.
hope thats some help
cheers
barri