Any ideas on how to get this cartridge out? I've tried to remove the nut but the whole valve under the sink turns as well. I did remove the clip after taking the picture. Thanks in advance.
You can first try removing the wire spring clip from the stem and then try to turn the bonnet nut assembly. If the whole unit still turns then keep the unit from turning by using channel lock pliers or vise grip to hold the unit in place. Make sure to use a towel to protect the threads. Once the bonnet nut is remove then twist out the valve stem.