So at the reduced price I bit the bullet and brought a new class 66 in DB red. Everything is good apart from the axle boxes, no matter how many times I tried to glue the central boxes on each bogie, they would keep on displacing. The inner and outside axles were fine after a touch of super glue on two of them which were loose.
I followed what others suggested and cut the backs off and glued in place , everything is now working perfectly and the the loco is extremely smooth.