Not everyone has suffered with this but because of the implications of a tail rotor failure, this mod is worth doing if you own an older TRex.
The new TRex's all have guides on their tail belt roller so this isn't an issue if you own one of them.
Sometimes when the belt becomes slack, it can jump off the tail rotor drive pulley in the tail case. This can cause the tail drive to jam up.
The problem I encountered, was the roller coming free from the bearing, which in turn caused the belt to drift to the side and jam up.
There are two easy ways to mod this roller. The first is to go out and buy a tail roller from an X-400 helicopter. It's a straight swap, and it has guides on the side just like the newer TRex's. The other method which I used, and works just as well, is to 'cut' a grove in the original pulley. To do this I just clamped the pulley in a drill, and with a cutting disc, I just ground the centre out of the pulley. It took about 2 minutes. Whilst the finish might not be as great as an 'off the shelf pulley', it works perfectly and cost nothing to make.
maz
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