My eight TBP12 beltpacks pre-date yours by about a year, Daniel.
All have plastic TA4Ms and you'll recall it was your post that prompted me to discover a possible problem with just one, caused by an un-noticed build-up of residue filling and lubricating the "groove and lip" that holds the TA4F's locking barbs.
After cleaning, all eight are still functioning perfectly, (I have two that are actually on people as I write this) so I feel that your "make good", while not "latest model", could be regarded as having been both effected and effective in this respect.
These are probably some of the first with XD-V75 printed on the front though, and whichever other minor changes that involved! I'm not too concerned with the plastic connectors. As you say, yours have lasted well, and it'll just be a nice novelty not having to tape mic connectors to the transmitters anymore!
It took me quite a while to cease being bothered by that sort of vastly varied cacophony, which is consistent with the racket that I've found to be routinely generated in any or all of my TBP12s whenever they're on without their inputs having been correctly terminated.
However, once their inputs ARE being correctly "fed" by any of my comprehensive inventory of sources, all I receive is pristine signal, to the point where I now regard the presence of any residual "nastiness" as an almost certain indicator of "upstream" failures in things like incorrect connections and/or batteries in phantom supplies and/or capsule contacts.
Unfortunately this noise doesn't disappear when a microphone is connected, it's just added to the signal. Two short MP3 recording links below if anyone wants to take a listen... Both from receiver XLR-out straight to preamp, no EQ, dynamics, etc. Output level on receiver at 0, dynamic filter turned off, encryption turned off, no EQ mode set on transmitter. Preamp gain at 25db.
NoMic.mp3 - transmitter turned on and paired to the receiver channel, with no mic connected to the transmitter. This is the noise you get when the beltpack is just sat on a table, then the noise as I pick it up and hold it against my back as it would normally be clipped on to clothing, etc.
WithMic.mp3 - Countryman B6 now attached (although it's basically the same regardless of which of our mics are connected). Preamp gain untouched from before. You can still hear the same noise is present when there's 'silence' in the room. Then you can hear me speaking into the mic at normal speaking voice, with the mic held on my forehead, as it would be in theatre use. Just so you can tell this isn't at ridiculously high gain.
A quick search on Google revealed an old forum post from a user who had the same issue some time ago, but with one of the V70 handheld mics. Unfortunately the fault was never diagnosed, because he just returned it for a replacement which was then perfectly clean.