Thanks for all replies.. Some of you might have missunderstood the situation with the shell.. I'll try to arrange some pics of it, although its hard to see.. Another problem might be that english isnt my first language. anyways.
The reinforcement rings have done their job properly. The shell isnt out of round. The drum must have been stored in a moisty invironment cause alot of the hardware was rusty. That was easily fixed with rust remover and alot of polishing.
The main problem is that the shell is somewhat uneven were the hardware used to be. The pressure from the hardware might have "pressed" the wood down making "cavities" were the lugs previously have been. The situation is worse at the "bottom" of the shell were the leg brackets used to be.
The shell seems to be so thin that it has "warped" were the hardware used to be.. that's the best explanation I can give at this point. There's no damage on the outer ply, all the 3 plies have been "warped".. yet again, the re-rings have done their job.
Hopes that explains things better. I would guess that Jayes interpretation is the more correct one. This is not a damage from removing wrap, more like a damage caused by years of a badly chosed storageplace and/or the fact that it's a very thin shell.