I do use a pair of Muller chokes but I am speaking from an independent point of view, not in anyway trying to fight their corner ! I am simply trying to understand what more Nick or for that matter Muller can do for you? You appear to have lost faith in the product .. don't use it ?? I really do doubt that there is likely to be a forensic diagnosis of the problem with this choke maybe there will it could be in Muller's interest to find out what happened here. You said you secured the choke fully but there may have been some sort of crud that actually stopped it being so fitted.. who knows? There are plenty of instances where a bolt or nut has been torqued to the correct reading only to find that a bit of crap was in fact causing the apparent torque and when loosened with heat or vibration a problem has occurred because it all falls out of kilter!