Markster.....I had a similar problem which after i took the regulator apart found that the control bladder had busted .....this is under the larger pressure knob in the bell housing...this part should unscrew...just be careful because there are about 3 or four part that will drop out ....it looks like a flat rubber disk....you might want to check that for any holes which causes co2 from escaping and little to no co2 comes out at the port.....

Alfred