Bulging Chassis Tubes.

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I think it really depends on how load bearing they are.

I had a couple that were starting to go that way.
Mind you a 3lb club hammer and a coat of paint worked wonders.

Mine was not on a restoration at the time mind you, oh and I cant weld  

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I had one on the very rear left hand upright of my mk2 obviously been full of water and frozen (it lived outside in the middle of a go kart track for several years) I ended up slitting the corner with a 1mm disk flattening the corresponding faces and grinding any excess due to stretching and then welded the corner - tidied up, you wouldn't know anything had happened and is still as strong as its fully welded.