I have a small assembly featuring about 10 parts. Amongst them is a representation of a compression spring, made by using 'coil'. The spring placed in the assembly ok and appears in the BOM. It also appears fine in the ipn I took from the iam and tweaked to explode the assembly. Lastly, it appears in the idw of the exploded ipn and its associated parts list. However, I can't get a balloon to associate with the spring. I even re-modelled it from scratch and dropped it randomly into the assembly and at that time, it ballooned - once. When I accurately placed it and deleted the original, it went back the same. Finally, I placed a couple of other unrelated springs/coils in the assembly and they did the same - ballooned once only. Any ideas folks? Thanks. Martin (UK).