I am experiencing a problem with the right engine prop control on my Twin Commander 680F. The prop operates normally for startup, taxi, run up (cycle at 1500 RPM with 500 RPM drop), take off (3400 RPM), positive rate, reduce to 3200 RPM, cruise climb at 3000 RPM. Then when reducing to cruise setting of 2600 RPM, the prop gets stuck at 2900 RPM. You can increase RPM, but cannot reduce RPM. It cycles back and forth between 2800 and 2900 RPM. After about 45 minutes, it finally comes down very slowly to 2600 RPM. After that it operates normally for descent, pattern, landing, taxi, and shut down.
I had the governor overhauled ($944.00), but that did not fix the problem. Has anyone out there experienced this problem, or have an opinion on what may be causing this issue..? We are pretty sure it is not a linkage problem. The airplane came out of annual in August. Thanks..!!