Dear hpt.... Great Questions, but I am short on any definitive answers to the Knoetel questions.
I am trying to acquire copies of the TN Magazine, "Die Raeder" from 1932-33, in order to try to solve these early uniform & insignia questions. (The oldest that I have yet been able to find is from 12/1935 - so it's not old enough to help with your question though.)
Bernd O, Doug O, Ernst H, Jiri Libal, Gary9 and many of the other TN & Police Collectors may have a much better handle on this than I do.
Littlejohn describes, but does not Show, the 1st TN insignia - as being an Oval (for both the Visor & the left Sleeve)- and then quickly moves on. DougO showed us his spectacular early TN Metal Logo / Wreath on his early TN visor - that was quite an eye opener & a learning experience.
I don't know what that 'TN Oval' looks like for this early time frame - 1933 - but I'd really like to see it - as would we all! Might it have something to do with the 'breast oval' in bullion, which was posted? Perhaps, as that nice TN piece is unidentified. (RonR posted another example of it on the WAF TN Uniform thread - so it is not a '1 of' item.)
The (unknown) manufacturer's metal TN insignia board, which I posted early on, has insignia from, what I believe is, 1934 forward.I base this upon the bottom row center device, which mirrors the TN Logo which was authorized in 1934 - and which is the same as the center of DougO's metal Kockade. (The date of the board is just my opinion, as it is not dated.)
More Technische Nothilfe mysteries - which hopefully you will solve for us! ...Txs, Dave/dblmed
