Morgan:
I don't know of a shop servicing the injectors.
Sometimes I have had problems with them not spraying well, wich causes poor running, and failure to pass smog (HC, usually).
I have had success with the following procedure: First, clean them with a cloth and 91% Alcohol - IPA, of course , not this kind
Then, I soak the injectors overnight, tips down, in a jar of Fuel Injector cleaner (the stuff you buy from auto parts stores).
HTH
Paul D. Young
http://www.deadpetsracing.com/PCA Nat'l Club Race Advocate
Now: '78 911SC, '79 911SC, '04 955-S, '06 997-S, '88 924-S, '16 92A
Past: '74 914, '78 911SC, '78 928, '80 924-S, '82 931, '86 930, '03 996-4S