Easy to take apart the lever, remove the cotter pin, spring and then the brass lever. One note, most times on the iron bowl, that brass lever is stuck. And the large nut with the wire mesh brass screen can be stuck.
In that case don't use pressure, or leverage or the handle will break, Heat up the brass nut and the handle with a torch, then stick it in a freezer,,the change of temp will contract the brass and the stuck parts will come free without damage.
Then lap with valve paste or I use TimeSaver, fine, good for brass too.
After lapping for good seal, replace with new spring and cotter pin. Get a spring at the hardware store and cut to length.
