Cutting and welding is the only way to go. Any other ways are not fixing the underlying cause and may introduce other weird and wonderful alignment issues. You would hate to put on the adjustable arms and wind it all the way in only to find it doesnt have enough thread. This would also mean a major difference in upper arm lengths.
Its a bit of work in dissassembly but should only be half an hour of cutting and welding. The idea of gussets as suggested would be a good move also.
Whilst you are at it, get rid of the orange juice bottle
