Hi Stéphane, I think I would look at why this is happening, what part(s) are warped and how the current situation effects the case parts (fallboard and keyslip(, the action regulationablity and if all looks like it will work then I would cut and glue on a shim under the front rail, then plane until it is properly bedded. I would check everything out before gluing it on, fall, slip, pinblock key blocks, etc. Don't do anything you cannot undo until you have checked everything out. Newton
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