yea, i kno that the spring is seated properly. that's no problem. and that bumper; i don't recall seeing that on your assm.

i swear i think your problem is that gap in the housing and the cartridge (why i could tighten the fuq outta the cap and it wouldn't meet the cartridge).

check around, and look on your website there sum more and see if you can find a detailed picture about replacing the cartridge it's self, so that we can see if ther's anything that sits on the cartridge while in the housing.