Paul,

I had to balance the feathering plate on mine. Here's a link to a post with some more information on this. I also have a picture in this post that should help. I don't know if this is a contributing factor to the vibration in your Corona, but it might be something worth looking into. You'll be able to test this out by removing the main blades and spinning it up with just the stabilizer. Mine had tremendous vibration with the blades removed. After I added the weight to the one side it smoothed out perfectly. Just something to consider.


http://www.rcgroups.com/forums/showthread.php?t=206441