It's not really a problem. The noise and vibration comes from the engine vibration. You can simply remove the play between the guide tube and the steel rod by installing some spacers. This is a part of the problem, and removing the play it’s a part of the solution!

Engine makes vibration and it's normal. RPM variation will make more or less vibration, if you have loose parts on the airplane (control rod, for example), there is a big chance to get noise! They also noise coming from the play between the wheel hubs on the bolt axle.....

Just balance your prop, add spacers to control rod, that’s it, or remove the vibration source by converting the plane to electric!!!