Was this at the point were it attaches on to the Sub Frames, I have seen these mounting point areas replaced? I don't see as to why they will not supply new Tubs, its not like they are very expensive like conventional CF Tubs, ie on the 918 its takes just over 5 days to make one Tub, on all Macs, its CF weave over layered with Injected resin takes 4hrs from start to finish and costs 12K USD on 12C and 650s. Mac used to have a chap that used to go round and examine all badly damaged cars for Tub damage.