[Mal Bridgeman]

1) Empty the set
2) Pick a valve
3) Undo the rubber knob (use fine pliers or screwdriver with a split in it)
4) Take care not to lose the spring
5) undo the big brass nut
6) undo the spigot to remove the actual valve seat
7) In the brass nut there is a nylon bush which can be removed by gently using the spigot
8) use a soft brush and white vinegar to clean off all the gunk especially the white grease from all parts.
9) Use your wife's ultrasonic jewellery cleaner bath to assist if you like
10) Dry everything with lint free material
11) smear a tiny amount of O2 grease on the valve seat threads, round the O ring on the spigot and on the nylon bush
12) Reassemble the parts ... don't overtighten the nut and make sure the spring is not done too tightly
13) Operate the valve and marvel at the ease with which is moves.
14) Move on to the next valve
15) Go to 2

When you then try valve drills next time you will be astonished at how freely they turn ... almost too freely so be careful when doing drills not to just keep opening and closing the valve with each hand movement

HTH
Mal