As with so many of these things just when you think you've finished with it you come up with another modification or improvement. One thing that became apparent after a few hours of use was the fact that the shafts running in the "A" frames was not as good a fit as I would have preferred and were getting a bit worn, causing vibration. A good blob of grease helped but I kicked myself for not fitting a proper brass bush in them as I had intended at one point, then decided it wasn't neccessary.
Then a member here who is making the same kit and fitted bushes to the "A" frames very kindly offered to make a couple for me and sent me two beautifully turned down brass bushes. Unfortunately I had to dismantle the back ends to enable me to drill out the "A" frames but I was able to do it without damaging anything and all the pieces were easily glued back together afterwards. The bushes were epoxied in place after drilling out to a nice clearance size to ensure that the shafts self centred and run smoothly in the bushes.
Anyway just a couple of shots of the process and since these the model has been run again and proved to be considerably smoother. The model will now last a lot longer and run so much more smoothly than it ever did.
All I have to do now is apply a spot of paint and look for the next modificatin!!