Just to wrap up this thread:

I sent my mic back to Beyerdynamic (in NY, USA). They subcontract all of their repairs to Sound Surgeon, by the way. They were very apologetic about it, and they turned the re-repair over very quickly, and I had my mic back to me in LA in only a bit over a week. Now ...

The volume was around "2" on the dial - but that doesn't help much.

Basically, the volume was not too loud for me to put my ear 4-6in away. The speaker may have been pushing a bit of air, but I would think that the grillcloth would dissipate this. Tuchel connection was solid.

However, it ...

yeah - actually that is a good suggestion, and i did try that.
I listened closely by ear, and I also put an SM57 right up on the speaker, and the distortion was not present...

I have an old (early 70s, I think) M260N with small Tuchel connector, and I use this w/ a Tuchel/XLR adapter cable. Anyway, I just got this mic refurbished/re-ribboned at Beyer in NY.

First off, let me say that I have little experience with ribbon mics, but I have done a lot of research to know ...