I agree with just pull the snap ring out and rinse with boiling water. Then pour in boiling water and tap with a hand pump tap to run the hot water out the dip tube (you do not have to put the ring in yet, just hold it down while you pump). Then fill the keg (water for me) and ready to serve (wait a week for water and it will start to carbonate.)
When putting the snap ring back in, do it so it ends at the slot. Hard to explain, but you want to be able to take a small screwdriver to pry it out next time. So line your start up just after the slot and push it in. You will need plyers to kinda crush it in as you go. Be sure it's all the way in.