Cheers every one, I suspect that wire wasn't tight enough as it was intact at the bottom. I will lag top to bottom with a tuck at the top followed by a very tight wire!
I had to chuck my bottoms away last week as they was covered in glass fibres! Looks like i will have to put some overalls on this time. :-)
I changed silencer for new one, but I kind of cheated, luckily the old silencer was rotten enough to allow me to snap it from the coupling in roof, otherwise I would of had to remove wood from roof to allow me to unscrew the silencer. The broken bit of the exhaust unscrewed with ease. I cheated with new silencer as I brought a coupling for the roof that allows the silencer to sit 3 inches lower than before, that allowed me to screw new exhaust into place without replacing tongue and grove wood on the ceiling. If the silencers had top and bottom inlet and out-let's in the centre, all the myther would of been avoided.
Ps I had her running with just pipe and it sounded lovely :-)