We recently completed a basement bathroom renovation. Our plumber did all the installation work but I noticed one of the two attachment screws on the shower diverted valve cover missing. Upon inspection, I found that the screw had been broken off. Having worked on all types of mechanical toys - motorcycles and cars - I've had my share of stripped and broken screws with the challange of re-tapping and/or removal of the offending piece. The Grohe diverter valve issue has me a bit miffed as my plumber assures me it's an easy fix. Unfortunately it's a 4mm stainless shank and the thought of trying to drill into it make me uneasy. Of course it my plumber's problem but I am wondering if anyone out there has suggestions. The valve is located behind a newly install surround.