Hugh's right, I am now on my third chassis. Both of my first two cracked on the upper chassis tube just forward of the back top wishbone mount and both were replaced at the factory, the second replacement being well after the end of the warranty period. Quite a few of the earlier chassis cracked where mine did, hence the various iterations of the bracing arrangements to reduce flex and fatigue in that area and the "not a recall" over the bolt on bracing. I haven't actually heard of cracking on the lower tubes before but only the factory will know for sure if it is a one off and if it is an area that the bolt-in brace has any effect on. If it is the factory that has suggested welding then I would suggest asking for the specification of the steel used in the tubing, it might be useful for the welder to know. Getting things straight enough shouldn't be a great problem, I'm not convinced they start out particularly straight in the first place and it's amazing how things straighten up after judicious application of brute force with a long scaffold tube, albeit backed up up with some careful measuring and a straight edge. Drilling holes to try and arrest propagation of a crack is a time honoured technique that generally has next to no effect...cracks have a habit of being much longer than you think they are and much less predictable about the direction they take than you expect, I've seen a lot of drilled holes where the crack has continued straight across the hole and others where the crack has turned a corner and gone round the hole. Good luck with getting it sorted out, a new chassis would be the ideal outcome given the various changes since 2012 but if that isn't happening then welding should be a good fix.
