Can you throw the compression release on with the engine running to tell if it has an effect without damaging the engine?Sounds like your compression release is not working properly. I would engage the compression release and spin the motor with the starter. If it spins the same as when the release is not engaged (rorw rorw rorw vs. whizzz) and especially if it starts, there's your answer.
Don't know about Bukh but Kubota (Universal) explicitly says NO in the manual.Can you throw the compression release on with the engine running to tell if it has an effect without damaging the engine?