OK, lets try this...
turn off the tank
turn off all bubble counters..
remove one of the needle valves that do not work...closest to the tank.
Open tank. SLOWLY turn up the regulator and see if any gas escapes...
If not you have a blockage.
you might be able to turn up the pressure to blow out whatever is obstructing the flow, but dont crank it higher than the low pressure gauge will go or you'll blow the gauge again.
turn off the tank
turn off all bubble counters..
remove one of the needle valves that do not work...closest to the tank.
Open tank. SLOWLY turn up the regulator and see if any gas escapes...
If not you have a blockage.
you might be able to turn up the pressure to blow out whatever is obstructing the flow, but dont crank it higher than the low pressure gauge will go or you'll blow the gauge again.
