Hi Guys...My friend has an Excell 60, SE I think, Here's the problem: In a hover his blades go way out of track, the thing "Woofs", has caused a crash a couple of times due to loss of control. We can't figure out what is causing it. At first we thought it was a radio problem, so receiver was replaced, then cyclic servos, battery, switch, all to no avail. All bearings are tight, feathering shaft was checked for straightness,( this has a Bergen head on it), we even tried different mains. We still have the problem...Any ideas?....Coop