Diane,
You raise good questions.
I am glad that Ric encouraged readers to thoroughly review my report. I was a TIGHAR Researcher at the time I wrote that, not a 'critic' per se, by the way. I began that effort in an attempt to answer off-site criticism stating that 2-2-V-1 was too large (vertically and by implication, horizontally) to fit properly as the patch. I was encouraged to do so by an administrator on this site. I hope all will find the report educational, whether one agrees with my own views therein or not.
As to the '307' feature: what was important about that find on the artifact was the possibility that it might align with the normal placement location for any re-established ring former section behind the 'patch' when installed in Miami, or subsequently; were that what the feature related to, it would surely reinforce the idea of 2-2-V-1 being 'the patch'.
What became disappointing to me (YMMV, of course) was that to get that noticeable feature on 2-2-V-1 to align with that station on the Electra - the most logical place for a vertical member to appear (why would one install a replacement vertical stiffener out of alignment with the existing remnants of the 307 ring former?), the artifact had to be slid forward to contact the aft edge of the next skin forward, in the 293 5/8 STA area. That arrangement, in my view (as stated in the report) is in conflict both with logical placement of the 307 'feature' and what 'should be' the forward edge of the 'patch'. In making that judgment, I am going by two things as to the forward limits of the 'patch':
1 - The patch logically assumes a similar outer-perimeter footprint to that of the coaming, which is easily defined by looking at the 'Nilla Putnam / Earhart' photo in Miami in which the forward area of the open window coaming is easily viewed, and
2 - An offset of the 'patch' away from (not abutting) the skin edge near STA 293 5/8 IS discernable in several photographs - a point of controversy, apparently, to TIGHAR whereby I am not officially qualified as a photogrammetrist and thereby cannot make more than an amateur statement in that regard.
I simply maintain that the offset (separation of the forward edge of the 'patch' and aft edge of skin near STA 293 5/8) is discernable to the lay eye in numerous photos, and note that TIGHAR herself has at one point or another in the discussion also believed the patch to approximate, logically, the footprint of the coaming. Further, TIGHAR has not so far established dimensions of the patch as being that large (able to pick-up 307 AND reach the aft edge of that forward skin near STA 293 5/8) - which would be one way TIGHAR might counter my report, if a credentialed photogrammetrist of TIGHAR's approval were able to do so.
Another oddity of the '307 feature' is the lack of fastener holes there - why bother re-installing that missing segment of the 307 ring former only to allow it to simply lie in contact without benefit of stiffening / strengthening fasteners?
You raise good questions:
What caused that mark?
Why does it appear on what would be the outer surface of 'the patch', and not inner - where the faying contact surface of the 307 member would logically reside?
None of the horizontal rivet holes in 2-2-V-1 coincided with the vertical '307' feature that I could discern - but as always, more scrutiny is invited. Also, 1937 is not reknowned as an era of structural bonding without benefit of mechanical fasteners, so the notion of adhesive in any structural sense is probably not a likely reality. This feature remains an unanswered enigma on 2-2-V-1 in my view, and could have come about in as simple a way as the artifact itself merely lying across some dissimilar metal object of that 'footprint' for some time by some odd or deliberate way - not necessarily as-installed in any airframe.
Just to be clear, I bore no particular spirit of 'criticisim' at the time of that report on this matter, nor do I now as to 2-2-V-1; it was always merely an artifact to be explored - and not vital to the Earhart case at Niku UNLESS it could be unequivocally proven to BE OF her Electra. To the extent I may be a 'critic' of TIGHAR would be based in other matters - NOT in the objective review of patch / 2-2-V-1 metrics per se. I consider my report to be one person's view, nothing more, and offer only that it has been 'peer reviewed' by two other qualified engineering persons (Messrs. Billings and Mark Pilkington, both well experienced in physical metrics and data interpretation as engineers / quality analysts). The report was also subjected to review by 'the Dayton Commission' here at TIGHAR, including Mr. Aris Scarla of the FAA, and additionally, Mr. Jeff Glickman who has been a significant contributor to TIGHAR in photogrammetry, and Mr. Joe Cerniglia, a frequent commenter and contributor of research here. All had some degree of questioning - all answered by me, but none offered disqualifying comments to me as to my work in that report.
As Ric has encouraged, I suggest readers take it in for themselves: I am not trying to disprove an Earhart presence at Niku - I have merely offered my most objective review of 2-2-V-1 as a supposed artifact of Earhart's airplane, specifically as to a conjectured fit over the lavatory window (an idea I actually initiated and do not regret, all possibilities deserving some review as I see it).
I hope this answers at least some of your good questions and clarifies my position in this matter, to whatever extent that may be important. I think it is important because while I may be a critic in some regards, this work must stand objectively clear if it is to have meaning. That was always the intent. I also will welcome a well qualified and quantified response to my report from TIGHAR should she find the specific means to counter my views and personal conclusions therein. Both TIGHAR and myself lack physical access to the actual Earhart Electra and her Miami-installed patch, so we are both forced to work from the historic record, such as it is. Fortunately for us both, I believe photographic evidence is sufficient, if not as ample as we'd hoped for.