U: Injector clean is easy. Just soak and spray with Carb. cleaner. ICU just spray the goes in and goes out ports with Carb. cleaner also. Spray 'till it run clean. Shake it in your hand to see if the plunger inside is free to move. You'll hear it click back and forth.
You can see the spray patteren of the injectors with the proper lighting and backdrop. Fill the goes in side with Carb. cleaner, then blow it out with your air hose and watch the patteren. Should be smooth and an even conical shape. I repeatedly cleaned mine and only about half had a nice pattern. There're only about $25.00 apiece new. If replacing, replace the seal, plastic holder, and O-Ring as well. My holders and O-Rings were as brittle as corn flakes.

Dave