When I worked in electroplating we used to reverse plate to strip the chrome and nickel for parts we were re-plating. This worked for even delicate parts (I once had to replate a set of saxophone keys!). So maybe Ian's platers left the levers in the stripper too long or they accidently electro-etched the brass before putting them in the plating vat (you do this to steel but not brass cos of the zinc content.
In theory, if you strip the chrome and ensure the nickel is sound you should be able to re-plate over this but it was only a fall back.
Try another platers with experience of vintage parts.
Thanks for the replies...
I suspected the fault lay with the plater as I've had many brass parts stripped in the past without problems (by this plater in fact) but wasn't happy with his explanation of the situation when I raised the matter wth him...These parts are too difficult to find to have them f****d up by an incompetent plater so I guess I may having to resort to posting them off to someone else if he isn't admitting to a problem...Ian