During the paint stripping exercise today I found  a split in the roof sheets, either side of the beading between the second and third bays at the top of the cant section.  I initially tried aluminium solder to repair the crack but couldn’t get enough heat into the panel without the risk of damage to the inner frame.  So although it is the kind of repair I despise, I tapped the panels down a little with the panel hammer either side of the beading and riveted a repair panel over each crack.  I should be able to fill over the repairs and shape back to the normal roof profile.