I expected a hole in the piston, but a borescope ruled that out, so a strip down followed, and this was the result:


I am going to drop the barrel at Langcourts to see if they can fix it, price a piston and see if it all works out cheaper than a new kit.
I have heard that MB have had problems with these RT kits, but not seen any other failures on the forums, is this true??
Anyone know what piston would be best to look at as a replacement??
Shaun.