I don't think you can just interchange any top plate for another in the M series. The M6TTL came out with brass top plates in the last issue of this series, but I don't believe you can put an M6TTL top plate onto an M6 body because the M6TTL is slightly (a couple mm) taller than the M6's because of the TTL flash circuitry. If you want brass, then you will have to try to find a titanium M6 top plate because the plating was done on brass rather than the usual zinc. Other than DAG or checking with service techs like at Kindermann (Gerry Smith is a great fountain of knowledge, btw) it might be hard to locate one. A few years ago, I noticed rust (typical iron rust, not oxidized zinc) spots on the flash hotshoe of my Titanium M6 classic. Gerry Smith at Kindermann actually had a replacement part in stock (i.e., with titanium finish) and so was a very quick and inexpensive fix. It won't hurt to consult the experts on this problem you are experiencing. Gerry is quick to respond to e-mail questions, so pick his brain for answers and the best solution for you. Who knows, maybe he has a spare titanium top plate lying around. Good luck.