CH Experts - Correct solution to renew seal?

[Best]

I always smear a wee bit of silicone grease on the washer when I change them. It will help prevent it sticking in future. (Not forever obviously).

Reminds me I used to unscrew the works from brand new draincocks and carefully wrap the rubber washer in ptfe tape to prevent it sticking. Used to do that on oil boilers where the draincock was directly into the boiler. Maybe a bit mad.
It is the heat that damages the washer, so if a draincock is installed on a long dead leg, or on a pipe that is dropped down below the rest of system, then the washer seems to last.
If possible it is IMO best to have a screw-in draincock, into a female fitting, so you just need to undo the nut and swap entire lot.
Some 1/2" screw in draincocks came with a tapered edge suitable for using a nut and olive, which is very handy.

 

[townfanjon]

Good point! No mention of tank fed, so going to be easy to take the pressure off system if it's sealed and replace washer.

Yep , “great minds “lol

 

[firemant]

If the jumper (mechanism) remains in the valve after removing the nut, the best toll is short ling nosed piers, to grip the stem and pull forward.

 

[firemant]

f the jumper (mechanism) remains in the valve after removing the nut, the best tool is short,sturdy, long nosed piers, to grip the stem and pull forward.
If the jumper comes out, leaving the washer, use a thick screw or a crew extractor to wind into the washer hole,then pull to remove.

It is best to buy a replacement cock. Remove the mechanism, to be ready to insert as soon as the assembly is removed. This is a type B draincock:

Midbrass brass plain shank drain cock (Type-B) 15mm | Plumb Center