http://www.denialville.com/replacing-faucet-valves/
I cannot get my faucet cartridge back into the housing?
I have a delta shower valve and I replaced the cartridge, but I cannot get the cartridge to go all the way back in to the housing. I do not want to damage it, what should I do?
The cartridge should be well greased with high temp stem grease on the o'rings, for easy install. First, make sure there are no foreign object inside the housing, then place the cartridge inside the housing, aligning the raised notch on the cartridge into the groove on the brass housing. Place the brass nut (threaded ring) over the cartridge, and tighten the ring down while applying steady pressure to the cartridge, making sure the notch and groove align- as you tighten the ring it will pull the cartridge back into the housing- for easier tightening apply stem grease to the threads of the brass nut. Hand tighten, do not torque down with pliers, this is not necessary.