Hi I’ve searched previous answers to leaking valve problems but I’m not sure I’ve seen an answer to this. Valve is leaking, tried tightening the nut, doesn’t really work, dissemble the valve and found like a damaged O-ring (see photo where the tool is). When assembly i believe the Small metal ring on the left Goes over where there used to be some kind of an o-ring. Is there such a thing as just an o-ring replacement or what part should I buy. Thanks in advance and sorry if it’s not super clear and I’m really not an expert in this.