Hi Thanks for all the reply's will try to answer all of them,
first up its a standard Hornby R8072 and it happens on a few of these, could it be just too small a radius? (im still building the main layout, this is a tamp layout on a board on the kitchen table) I have some express pecos to go on the main layout.
this happens in both directions and the bogies are free turning, I have added a washer on the top of the bogie's to make them a little higher so they dont snag the frame.
as for the watching with headphones, in the slowmo it makes quite a thump as it comes back down! lol
not sure what it is that's making it hit the V of the points but does seem to do it on all of them, its a great runner on a loop but does not seem to like changing tracks :P
Cheers
Daz