auto water feeder not working

weil-mclain SGO oil fired natural draft steam boiler. steam radiators, the old 4' high ones that hiss and they chain you to in the old movies. tankless hot water. uni-match universal water feeder. mcdonnell&miller. model # WF2-U-120 furnace stopped working. i found the water sight glass empty. pushed the red button on the water feeder, could hear water flowing. stopped for a minute. tried again. now it just buzzes. is there anything i can check, like maybe it is just jammed or plugged up? I see it has a drain, they recommend draining and cleaning a screen. is that worth a try? i hate to call a tech, just to have him whack with a wrench because it was just stuck. i am pretty good at whacking things with wrenches.