same thing happened to me...Brought an mbw 1680 case, 703 yuki tube, and 1.2mm gen springbars to a local watchsmith to get the lugholes and tube hole fitted. Explained to him what had to be done and the watchmaker comes out of his work area and tells me, "Its aftermarket sir, It wont fit!"
I thought i explained it perfectly the first time and say "Yeah thats why I want it modded for the bars and tube."
He tells me, " I wouldnt touch the CASE if I were you. Just ditch springbars and wrong tube and and get ones for rolex and your good to go."
I explain to him again thats its "aftermarket" and he tells me that he wont touch the gen case...ha ha