Dapols stupid driveshafts!

[AndyGif]

This may well work, but the driveshaft isn't the only feature that won't have been designed for 9" radius, it was just the bit that hit problems first.  You'll also find that the rigidly coupled wheels on larger steam locos don't have enough sideways play to go around smaller radii, and the pony wheels may not be able to articulate far enough.  This is the price we have to pay for valve gear which is somewhere near scale and smaller flanges on thinner wheels.

Indeed it is the price you have to pay, for accurate steam loco's.
I only have one steam loco, and thats a 9F, bloody thing wont through my only large radius curved point  in either of  2 tracks  in to 1 direction even at low speed, going the other ways its fine.
so there it sits in its box, waiting to go in the display cabinet with my collection local coal wagons.
Just as well I model BR Blue period, i'd have gavem model railways up by now if i was into steam.

[EtchedPixels]

If your 9f hasn't had the Dapol fix kit applied then ask Dapol. There was a problem with some that got rectified later, and a fix kit for old ones.

Otherwise why not return it as faulty ?

[AndyGif]

If your 9f hasn't had the Dapol fix kit applied then ask Dapol. There was a problem with some that got rectified later, and a fix kit for old ones.

Otherwise why not return it as faulty ?

Nah, its fine on everything else but that one point.
Yes it was already fitted with truck mod.
Its probably just a badly laid point and its now a couple of years old. Keep saying I'm going to add a lead shims to the truck to see if that stops it bouncing off the track.