I am looking at a 4/4 which is in excellent condition with the only thing I can find is a slight bubbling on the paintwork on the joint on the body below the door. I think it is the joint between the rear quarter panel and the fishtail panel ?

The paint is intact but has some minor bubbling so assume some corrosion? Other than cosmetic is this something to worry about does it indicate an issue with the ash frame

It’s a 2001 model

Any thoughts would be useful