this may sound really stupid.....
have you purged both regs and/or LP inflator? Honestly, I have had cases where one reg was somewhat pressurized and i got that "pop" or had trouble removing the stage from the tank.....
have you purged both regs and/or LP inflator? Honestly, I have had cases where one reg was somewhat pressurized and i got that "pop" or had trouble removing the stage from the tank.....