Yeah, you probably have a '00' or a '000' metering or restrictor unit. Hard to get air to pass thru one that small. Best thing to do is crack the nut down stream of the restrictor and let the oil bleed out. If it doesn't, then replace it. They do get clogged up from many years of use. There is a filter built into the metering units or restrictors that get clogged up.Cheers. Yeah I'm having trouble getting air through one of them.