If it's a typical ASV device built into the valve top as so many valves are today, the lid does screw off. You gotta use the pliers, but use a large set of 2 wrenches to hold the body steady while "breaking" the top loose. Careful, tho' and be ready to replace it if things go wrong. If some yokel overtightened it, things could break. It's a crap shoot..... good luck!
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