1991 Genesis side burner gas hose threads

I'm hoping someone here can comment on the type of threads that connect the gas hose coming from the manifold to the valve of the side burner.

My grill was purchased new in 1991. Looks almost identical to a Genesis 3000 but the tank level indicator is straight instead of dog-legged. Maybe it's a Genesis II?

The hose from the manifold was chewed by wildlife a few years back; I disconnected it and put a cap over the fitting at the manifold (3/8 flare I believe). Unfortunately I did not save the hose.

The side burner valve has a 90-degree fitting with what seems to be a 1/8in NPT female connection. However, I picked up a brass 1/8 NPT male connector at the local hardware store and found it only went in one turn before stopping. Threads are clean, by the way. I am reluctant to apply much force (i.e., wrench) until I know for sure that I have the correct threads.

I do have a spare tank hose like this one, which does thread nicely into the valve fitting. Are there subtle design differences between what I find at the hardware store vs. what Weber used on their grills? Or did I just get stuck with poor tolerance machining?

A second question: once I understand the thread issue, I am considering modifying a gas hose I already have by installing a threaded adapter with hose barbs + hose clamp. As I understand it, the regulators reduce the gas pressure to 11in WC, which is around half a psi. I think therefore that hose barbs + hose clamp should have no problem. It's nowhere near the high side tank pressure 100-200 psi. Agree/disagree?

Thanks!

Maybe put up some photos

Is it possible to find the manufacture plate and post the Model number thanks... this will help us. Pictures work as well.

Photos follow. I couldn't find a mfr plate, but maybe I wasn't looking in the right place. I'll go out and look again.
(Left tray and lid handle originally wood, replaced with new wood. There used to be a flip-up tray as well, not currently installed)

Grill:


Valve with threaded elbow:


Valve elbow threads:


Valve with 1/8in NPT adaptor inserted, only goes 1 full turn:


Valve with tank hose inserted, goes about 4.5 turns:


Spare tank hose:


Spare tank hose threads:


Not enough hands to hold camera, threads, and caliper, but left caliper at correct measurement. ID of female threads will naturally be smaller than OD of male threads because of height/depth of thread.

Caliper measures valve threads ID .329in:


Caliper measures 1/8 NPT adapter from hw store .396in:


Caliper measures male threads of spare tank hose .385in:

For the sake of anyone finding this thread in the future: I got another 1/8 NPT adaptor from another manufacturer. It fit! At least three full turns. So it looks like my side burner valve fitting is indeed 1/8 NPT.