The bleeder screw is a mechanical dip tube fill level indicator. OPD valves, gauges can get it wrong, Not an actual level device. There is a tube that goes into the bottle or tank to the 80% full point that will 'spit ' liquid ' at that level.
If it is leaking, it does need serviced, likely just an o ring. The tank will need to be empty or emptied to replace the seal. The short time to do the service should not require purging, however the technician is in charge.
Ive never seen a fee charged for recertification for portable or mounted or leak repair if you refill at that dispensor.