Anthony the whitish material looks more transparent on the threads. I will try an download a picture but my cheap point & shoot which actually takes pretty good images just eats batteries, so it may be difficult getting an image to you quickly,
It could still be teflon tape; after it gets used, I find that it does turn transparent. In any case, a photo would be much more helpful, particularly for the next part.
However I can try & describe it better. All it looks like is a T that comes off the left side directly off the central hub if you will of the regulator. The top part of the T there is a fitting that the CO2 tube is delivered to the solenoid. Looking just left of the T there is a small hex nut & then the dial itself for adjusting the flow.
This sounds like there is an additional valve for adjusting flow, in addition to the regulator. You can probably remove this to clean up the appearance.
Does the needle valve go in that part or does the whole T have to come out & be replaced as an assembly?? Once again looking right now you have adjusting knob then hex nut connecting to the T pointing up which goes to the solenoid, then extending with threads directly to the regulator, this is where I noticed some kind of solvent that is clear looking. Not tape.
Thats it: My guess is that small hex needs to come out to get at the needle valve & then replace with new one.
A photo is needed. If it is an actual T, then the needle valve can go into the T. In general, needle valves go after the solenoid as well, so I am unsure exactly what kind of setup you have.
You asked about which needle I have & I cannot find manufacturer label anywhere on the regulator or needle valve. Looks like no name bran.
No name brands tend to have unusual/proprietary fittings, so you may need additional adapters and/or fittings as well.