Dr. Benz,
You are right. I just called it magic because that is about the extent of my knowledge.
Peter,
I used my thumbnail to clean the injectors believe it or not. I have a stout thumbnail, and kept that way for purposes such as this. You use the nail to pull out the spring loaded pintle in the center and work your nail around the part that seats to the rest of the injector. You need something thin and strong and a fingernail is just about right. It may take several tries if there is some build up. Keep in mind that a really bad injector will never correct itself. It has to do with the spring, pintle condition and the seat.
I have a few NOS injectors and the difference between them and a "cleaned" injectors is staggering. I sure wish they would make a run of these damned things so people with 220SE motors can have one less worry.