I am trying to repack and rebuild my silencer it looks like crap and is missing almost every rivet. anyway I did some searching and it says that the top case of the silencer slides off the back. i tryed that and couldnt get it to move more then like a cm it just looks like its gonna go easier the other way does it actualy slip off the back. its an 01 powercore 2 silencer for an RM250. also i am replacing my endcap mine is pretty mangled up it measured around 1.3inches but thats rough because its all dented up I see there is an option for a 1.375 is that the right size for that year of a powercore 2 for an rm250?