Anybody know Victor flowmeters?

The flowmeter I'm curious about, the HRV2380, has inside it a device called a "cartridge". This is apparently the problem with my meter.
The cartridge has a sintered metal filter in one end and the other end has a small hole with a stiff wire protruding. Pressing on the wire allows more gas to flow. The one I have flows gas even when there is nothing pressing on the wire. So there must be something inside the cartridge that prevents a valve from closing all the way. Anybody here know what is inside these things? I'm probably going to take mine apart when the new part arrives but I am impatient and want to know now. But I don't want to take it apart until the new one arrives just in case I need to fix the one I have. Eric
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