Someone that can recap/refurbish/recalibrate a direct drive turntable motor?

Interesting Thread Policing going on.

"I'm interested in anything that can improve my motor. Is your friend currently taking new business?"

There are others on DIY Audio and other forums who have fully overhauled this  TT model and other Japanese Vintage TT's. These individuals are very open with what they did and have assisted others successfully with Trouble Shooting operational issues, these individuals are easy to find and do seemingly reside in the US.

My suggestion is a viable option to consider for the OP, as investigation could discover a local support might be on offer. Who knows? A good friendship might be very close to taking root. There is zero harm being done if a few more of these are able to be cultivated. 

I feel very confident the OP would very much enjoy learning of Panzerholz in use as Plinth Material. Especially as material that has been selected by quite a growing number of TT users, where the P'holz has superseded the use of the earliest  designs for a Plinth. I am sure the OP would like to know about cases where the use of P'holz has been very convincing, encouraging other materials such as Stones, Resins and Metals to be superseded in use.

I'm more than satisfied with my discovery of the different producers of the material known as a 'Phenolic Resin Impregnated Densified Wood', of which Panzerholz is a Brand name for it.  

 I'm more than satisfied with my being an advocate for the use of Densified Wood, enabling others to learn more if wanted. 

If you can select quotes, I can select quotes, too:

"My daily driver is a JVC TT-81 in the dual tonearm JVC plinth, but lately it’s been pretty flaky, e.g. noticeable flutter, along with an occasional speed runaway and strobe not reporting correctly even though the speed is clearly close."

This is indicative of a servo problem. All the bearings and all the Panzerholz in the world is not going to fix the problem described in the OP. That’s all I am saying. I know your suggestions are well meaning. If armstrod lives in the UK or on the continent, perhaps you know of someone with the skillset to investigate the servo of a JVC turntable. That particular mechanism is very complex. I bought a malfunctioning TT101, which might be even more complex than a TT81. I spent two years and sent it out to 2-3 gurus over that time with no success. Then I found JP Jones through internet revelations regarding his work on Technics SP10 TTs. JP found and fixed the very esoteric problem with my TT101 in about a week (a cracked PCB tracing that was obscured under a blob of solder). That was more than 5 years ago, and the TT has been functioning perfectly ever since. Others have had similar experiences. No disrespect was intended.

If there are variable speed controls, either external or internal, they may need a shot of Deoxit in the green and black can. I've seen controls get noisy and cause exactly the complaint described. Photos I've seen of this machine don't show speed controls but that does not mean that they might be inside.

Its also old enough that if you plan to continue using it, the capacitors in the power supply should be replaced. If it were me I'd replace all the other electrolytic capacitors in the unit too.

I think the TT81 differs from the TT101 in that the latter TT has external buttons to increase or decrease rotational speed in small, regular increments. The TT81 does not have that feature, so far as I know, but as you say there are likely to be potentiometers internally that do modulate speed. As I understand it, adjusting such variables is part of what it takes to calibrate a DD. The servo mechanism was also described by JVC as being "bi-directional". My TT101 had the following issue when I bought it: At start up, the TT would come up to speed, but in the speed display window, an erroneous readout would appear, for example if set for 33, the digital speed readout would show "33.32" or "33.34". It would go on this way for a minute or so, and then it would stop dead. The brake would not actuate to stop the platter. The digital readout would disappear leaving only a decimal point lit up, and the platter would coast to a stop. What’s worse, the problem was intermittent but frequent. Bill Thalmann could not reproduce the failure mode in his shop. Nor could one other repair shop to which I sent the unit. Finally, I fiddled around with it enough that I made the intermittent problem into a regular occurrence. (Which is to say, although I had no idea of the real problem, I made things worse with whatever I did do.) I then found out about JP Jones and sent the unit to him. He had never worked on a JVC DD prior to working on my TT101. He found the problem described above; the PCB had cracked across a tracing which defect was hidden under a blob of solder. Apparently the JVC PCBs are hygroscopic. They absorb water from the atmosphere, swell up, and can thus damage a tracing. Once discovered, this was an easy repair. Since then I have found the TT101, with beefed up plinth and specially fabricated aluminum tonearm mount board, to be a superb TT.