Thanks for your reply.
Could you give me the bump settings you are using in that screengrab please? Are you using standard max noise or Bercon noise? Also, what UVW mapping are you using on the polyobject?
If I use a large box mapping on the railclone object, say 10000x10000x10000mm, will that give a 'seam' part way accross the panels of glass every 10000mm?
I'd ask you to send me the scene, but I am on Max2009 and I would imagine you are creating it using something newer.