A few pictures and things that may be helpful.
The piston/air valve on the left is the fixed type - on it you pull the needle out from the bottom (after removing the side grub screw). If you can't see anything but a solid bottom with a dimple as you look down the tube with a light, this is what you have. The one on the right would have a star washer to keep it in place from the top.
This picture shows a carb with the jet in and a loose on sitting on it. The extension that reaches into the fuel is thin and bends under pressure, so for pressing it in you need a stiff ss tube or other suitable drift that presses in on the shoulder and not the extension (but that fits within the body). I'm also attaching a Lotus service bulletin that addresses jet height (how far below the jet face should be from the inside bottom surface of the venturi/choke. Note that this carb has an extra tube extending from the mount - I don't think this was a Lotus carb. The second picture shows the mount flange of a Lotus carb with markings identifying its series or reference number. The final picture is of a page from the Zenith Stromberg booklet published by Burlens.