Hi,it looks like I have the one with a relief valve in the plug and there is a o ring inside which may have failed,not many of these were produced apparently thanks.

Hi,looks like I have the one with the relief valve built in,anyone know about these. Thanks.

Hi,I have just got a fill plug for my aa400,this is different from my original as it has two brass parts in the cylinder end,and when fitted air was vented from a hole in the have I got the wrong one? Any ideas. Thanks.