As you already know if they were working fine they are probably not dirty.
I took a Magnifying glass and visually inspected each tip to see if I could see anything.
First I removed the O-Rings from the injectors, I put a small amount of sea foam in a cup and soaked just the tips for about ten minutes. Tap them to get the air out so the sea foam gets into the injector.
Then I took a brass wire brush and carefully cleaned the carbon from the sides.
I rigged up a 9 volt battery with two alligator clips to actuate the injector.
I turned my compressor down to 20 PSI, and put the air gun in the vise. and had a spring finger clamp to hold the trigger so when I was ready it would deal with itself. If you don't have a compressor you can get cans of compressed air for computers and electronics anywhere.
I actuated the injector and poured some sea foam into it. brought it to the air and blew it out back wards quickly so I did not actuate them too long. I went down the line and did all six. Then went back and blew them out the other way. You can see them spray, and watch the pattern if one only mists out one side you would see it.
I cleaned the terminal pins on each injector with a nail file.
(You would probably need some mission impossible music
to get past your bride who is no doubt still Pissed about the whole valve covers in the oven incident
- How are you healing by the way?) I scuffed the tops and bottoms of the pins. When the file gets dull clip it down with a pair of dikes.
I replaced all the o-rings (although the old ones looked OK) they were .92 cents each-$12. after you put them on the injectors lube them before you insert them so they do not tear. I use Vaseline (but just in case you are still on the Lamb with the nail file) engine oil is fine. BMW and Land Rover use the same size o-rings if that helps any.
Put some DI-Electric grease on every terminal before you put it back together. I use it religiously I'm originally from NY and the salt is attracted to the static. A friend of mine says a $5 tube makes half the difference on a BMW tune-up.I just slide it across the 2 metal females in the plastic terminal and fill them that's enough.