I have a 20 year old home and the upstairs bath has a single handle delta faucet that has developed a leak at the tub spout. I removed the faceplate and sleeve from the faucet but don't know how to remove the inside cartridge. A very nice step by step set of photos on line shows a different type of o-ring fastener than I see on my faucet. I see an outer bronze ring with 2 slits (one on the top the other on the bottom). The top slit looks like it has a clip sticking out of it from inside and this may be the lock that holds the cartridge in. However, I can't see any easy way to get at it. Any help will be appreciated.

If your mixing valve's 20 years old then chances are it's this one.( see inage).
Work down to the seats and springs,(see image)and replace them. Delta has a repair kit, (see image) that you might be interested in installing. Good luck and thank you for rating my answer. Tom

DMK112, You gave me a reddy,(disagree) on someone else thread. Would you care to explain why?