This is a D-jetronic system with electronic fuel injectors and a metal rail running a circle above them, right ?
I have a .zip file I send people with the various diagnostic procedures and system descriptions. You'll have to send me an email so I can send it to you.
to replace one injector usually means pulling the whole rail. Buy the TWO rubber bits for each injector. They're like 3$/injector. One piece is a rubber boot on the tip of the injector. The other is the ring on the injector.
There are no special tools required other than a C-clip remover (if you change the rubber rings on the other injectors). But to check out the system correctly, you should have a fuel pressure guage that reads in the 20-40psi range (correct system pressure is 32psi).
It doesn't hurt to replace all the fuel lines if they even look old. Also there is an incredibly critical hose from the manifold to the manifold vacuum sensor (mounted under the brake booster last I saw). Make sure it's brand new. A little vacuum leak goes a long way.
Of course, if your motor is CIS, then "never mind".