Stamp ID Request: US Scott 208 Or 186?

Greetings:

I believe the stamp in the photos below is Scott 186. There are four vertical lines exterior to the portrait frame (see inset photo). Your conclusion? Comments are appreciated; thank you in advance.

That's a National Bank Note printing.

By this do you mean it's either Scott 137 or 148?

No grill, so 148?

Yes.

Yeah, agree, color is perfect for the 148.

Too bad. It's a nice stamp, and I actually need a 148. But it's the second time the same seller has provided a stamp that was either mis-identified or (in a previous case) had undisclosed flaws. I stumbled upon a very useful StampSmarter.com page only after I started this thread. All replies are appreciated.

I read this is a dormant topic. But the title is exactly what I was looking for. I recently pulled this item from an APS CB. It was described by the seller as a 159. The secret mark was there on the ribbon but looked heavier than normal using just my eyes.
Under the microscope there are seven enhanced vertical lines at the left of the left lower ribbon. Scott describes the mark as just four.
Next I checked the left border, thinking this item might actually be a 208. But there are four vertical lines on the left border, not the three Scott specifies.
Looked at Siegel's site at 30 mint 186's recently auctioned. All 30 had the 4 border lines and the 4 enhanced ribbon lines. Looked at 30 mint 208's and found all 30 had the prescribed 3 border lines and 7 or more enhanced ribbon lines.
Checked the USPCS and Stamp Smarter site's and did not find an answer why my item does not match either the 186 or the 208 definition.

Looking for suggestions for further research.

You will find better matches if you start looking at 148's #128578;

Thank you Sinclair. Did not think to go that much earlier.

So the first secret mark was created by reducing the shading on that part of the ribbon on the 148 design. And years later, the shading was increased to something like the original.