I can't help you with a mechanic but there are some good videos on rotax-owner.com that show how to do it. I had never done it but after watching the videos, I borrowed a CarbMate and synched mine. The engine idles better than ever.
So I think the video's are very helpful if you haven't already watched them.
John D. Young, RV-12 Owner
Serial Number 120022, N6812Y
Bought it as a flying airplane in Feb. 2018
Just passed 100 hours flight time in RV-12, and 10,000 hours mostly in corporate jets. I am a CFI; CFII; MEI; and a advancd Ground Instructor, CFIG; and hoping to be able to help new RV-12 owners by doing some transition training for new builders and owners in RV-12's.