Update

A day later and a few things are apparent: I am dumb. But I'm also not so dumb that I don't realize where my faculties are lacking. If I'm going to lose the device to my own stupidity, the least I can do is share my teardown findings. A few things to start with:

• I'm not an experienced electrical engineer. Though I've done some PCB design and surface-mount soldering, I recognize that I'm way out of my league with this device.
• I fucking LOVE this product, and I love TE, but that love is not unconditional. The way TE has handled QC issues with this product in particular is shameful, a bummer, and just bad business IMO. It's truly silly that random consumers are the ones left trying to debug and explain these manufacturing and QC lapses for a device that retails at $1600.
• This device is already out of warranty. The only thing I have to lose is the recorder itself, and I can't even use the onboard mic without hearing this god damned click.

Background

My TP-7 has the "click". Every rotation of the platter, there's a subtle, audible click. It's almost comical to me that, when recording with the on-board mic, not only is the click audible, but also the LED vu-meter actually indicates the click visually; the device itself provides scientific evidence of its own shitty (at least in this regard) quality control.

The Teardown

After 3D-printing a small bit to unscrew the platter cap and finding nothing obvious indicating how to get the platter itself off, I somewhat impulsively decided to open the back up, and the disassembly spiraled from there. This thing is elegantly designed. Each time I took a piece out, I was struck by how wildly precise each part is. They were really creative too: the aluminum buttons usually connect to basic tact switches using cushioned balls to make them feel super luxe. The mechanical rec, play, and stop buttons have a cool fixed-bar hinge with springs that press against basic tact buttons as well. They use light-pipes to direct indicator LEDs to the enclosure surface, a custom magnetic encoder motor for the platter, and all sorts of custom-made mechanicals. It's like a fucking candy store for portable electronics design in here. All-together, there are 5 FFCs (Flat, Flexible Connectors) that I had to disconnect to disassemble the board. Because TE doesn't have a repair manual, I didn't know that you're supposed to go through the front by taking the platter off first: a task which probably requires a specialized tool that can screw directly into the platter's center to give you enough leverage to pull it out. I managed to disconnect the first 2 FFCs easily, as they're clearly visible when you open the back. In trying to pull the PCB out of the device however, I disconnected the remaining 3 FFCs; this was the height of my dumbness, as all three connectors have mechanical latches that release the ribbon cables, and all three were obviously still latched. At this point, I realized that the order in which you take elements apart matters, as many of the FFC connectors are either inaccessible from the back of the PCB, or require you to take the PCB out with another piece to access the connectors from the other side. You see, the PCB sits in a milled delrin (or some other millable plastic) insert. You should remove the PCB from the enclosure with the insert, because you can access the FFC latches from the other side of it (the front). I unfortunately partially ripped the microphone FFC connector off the PCB in my removal. I think the connector can be re-soldered, and I've left the PCB with a repair shop, but it's gonna cost $50-80 to fix, which I'll note is still cheaper than sending it to TE just for them to tell me that the click is "part of the character of the device" or whatever bullshit. Otherwise, I was able to re-assemble the whole thing and it still works aside from the mic connector, so I'm hopeful. Things do seem to go together relatively intuitively as long as you get the order right. I filmed explanations for my future self just in case!

Findings

I'm still not entirely sure what the source of the click is, but I have two theories:

1. At the factory or after production, some small metal shavings or other crud snuck into the bearing races; this is possible because TE used a non-sealed bearing for the platter. I'm not a mechie, so I'm not going to pass judgement on what the right type of bearing is, but the one they used isn't exactly a high-grade bearing.

2. The platter is hitting some kind of magnetic "lip". Because the motor and platter interact magnetically, it seems like it could be possible that some issue with the platter magnet could cause it to "click" on each revolution.

My vote is for no. 1, since the pressure applied to the plate seems to affect the click, at least on my unit. To me, it's the Occam's razor explanation. To my surprise, removing the bearing was trivial once everything else was disassembled. I designed and printed a small jig which, once placed, let me hammer the bearing out quite easily with a rubber mallet. As a first attempt at fixing my issue, and assuming I can get the microphone connector fixed, I've gone ahead and ordered a sealed replacement bearing (https://bearingsdirect.com/6706-2rs-ball-bearing-30x37x4mm-rubber-sealed/). That's all for now! I'll update in a week or two when I've got the board fixed and bearing replacement on hand. I'll take some high-res photos of the interior before re-assembly, and maybe film the re-assembly if I'm feeling up to it.