Fuel injectors - how to change the seals?

[Radek]

Hello fellow Audifans/Audisufferers;

Patient is a 1988 B3, NG engine.  In order to get to something cracked or not tight in the exhaust manifold or the vicinity, I am removing the intake manifold (seats on top) to take a closer look.  I thought it would be a good opportunity to change fuel injector seals, which are in all likelihood 25-years old.  The injectors came out VERY easily, but they are held inside a black plastic sleeve that I can't remove.   Is there a trick or should I just pull and twist patiently?  BTW, separating the injector from fuel line is not practical, because everything is so rusted, the line would probably break.  In other words, I can only pull the sleeve down, towards the injector tip.  Any BTDT?  Thanks.

Radek
88 90Q
91 V8Q 5-sp