I converted a couple of the Hornby China production tender drive 9F's to loco drive, and they put in half a dozen years service, until superseded by the Bachmann model. The rods proved to be the one significant weakness, despite attention to lubrication of all joints: I have had to replace rivets in rod joints, a return crank, and three out of four motion brackets fell off the plastic bar which secures them to the chassis. I assume this last is what the OP refers to. No complaint about this, having modified these models I was quite happy to repair what arose. But it does suggest to me that unless Hornby have beefed up these components the same things are likely to arise on the new loco drive version.