Right just checked, mine has a loose part, can hear it!!!
Bugger, will be well out of warranty, I shall get an R6004FF and hook it upto my Futaba.
Good spot and v interesting that mine is the same. I'd have to say peeps check your rx's on the 4 channel, might be a weak piece which is easily dislodged?
Purchased mine from Miracle-Mart
Pitt