Hi Frema,
It sound something like that...
this bass tone was previously heard, with some vibrations, at maximum throttle (i.e 150K) but lately this tone came more obvious even at lower turbine speeds.
last time we heard it even at start-up ramp at approximately 30K.

another thing, i have a second RAM500 that takes much longer to slow down to a hold.
this might indicate a bearing problem, i guess ill have to take it apart and look.

hi Xairflyer, thanks for the picture, it sure is helpfull.