I recently had my cmc6/mk4 mics cleaned by Schoieps. The shipping was about $70 for the two mics - and the work was about $175. They cleaned and tested the cmc6's, cleaned, replaced small parts, tested, and adjusted the mk4 capsules. OI know yopu only need an active fixed but that may give you some idea of the price range. I had my work done through Redding Audio - excellent people. If you go that route the # is (203) 270-1808. Ask for Scott Bolan. Takes about five weeks. Best of luck!