Near the top, on the end opposite the supply valve, find the small bleeder valve, which must be opened to let trapped air out.

Many bleeder valves are slotted and can be operated with an ordinary screwdriver.

Hold a ceramic or thick glass cup, or a pan with a handle, under the bleeder valve.

The stinging ozone of liquid oxygen vaporizing from bleeder valves.

Many bleeder valves are slotted and can be opened and closed with a screwdriver.

Remove the little bleeder valve from the radiator by unscrewing.

Anyway, I diddled with the bleeder valves an' the piston boosters.

There's been some trouble with one of the bleeder valves in the chamber; the pressure is above Mars norm.

If it is only partly open, the bleeder valve might be clogged.

If this solves your problem, buy a new bleeder valve and install it.