We had the same problem this spring with our twin when a few bees
dcided to crawl into the pitot tube. We ended up having to take the
rudder off to disconnect the tubing and then we could free the blockage
of bee and nest with a piece of wire. It was a real pain and took a
few hours to complete the repair, but it was the only way...after we
tried a couple hours of what you described above

Adam