I had to replace the bellows on my 265 a few days ago. The new bellows came with a 2 sided instruction sheet.One side for the bellow the other for the flush tube. I also managed to dislocate the flush tube in putting the new bellows and thought I was in trouble but by rotating the flush tube, in position in the top tank, before attaching it to the bellows I was easily able with a pair of long nose pliers (probably essential) to pull the tube nozzle back into place on the bowl edge.
I have a scan of the Thetford instructions that came with the new bellows and can E-mail them out to anyone but I do not know how to put them on this site.