Can I repair a washing machine shutoff valve?

[Plumbing_Steve]

My townhouse is all piped with PEX which I am not equipped to work with. In the process of replacing the hoses to my washing machine, I've discovered that the shut-off valve is not working perfectly. It still lets through a constant drip of water. Is there anything on these valves that can be tightened or fixed?

https://imgur.com/a/hGHvT

 

[Geofd]

I can't see the pic but that could be me is there a brand name

is it single handle
a seperate hot and cold??????

I have valves similar to that mine is also in pex I secured
copper f+m rrings so if..... I had to change the valve it would
spin out easily

just shut off the water bleed out the pressure and back it out
you will know right away if it starts getting loose



I think the way you remove the valve is hold against that nut/washer
I think that holds the brass nipple in place then spin off the valve in question

I looked at it again looks like a plastic threaded washer sits flush
on the box then a brass nut then the valve hold back on the brass nut
then spin off the valve

 

[Plumbing_Steve]

Like this but brass:
https://www.oatey.com/2373007/Product/Oatey-

 

[havasu]

Here is a better pic.