@lewm There are a range of experiences to be encountered when buying into vintage equipment. Limit these experiences to TT's and investigations will show up a variety of TT's that have undergone refurbishment or serving of some type.
Limit the TT's even further to Vintage Japanese DD TT's, investigation will show up, that there are plenty of TT's having needed work undertaken. Commonly it is seen to be operational issues where the TT is showing anomalies in how it is functioning. Usually these are resolved by a EE with the right skill set, or enthusiasts with adept EE Skills.
You went for the support that is offered from a business model, this is not the only option. I have encouraged the OP to look at an alternate option, not to push them away from your suggestion but to broaden their knowledge base.
I myself converse periodically on Two forums and have face to face discussions about the Vintage Japanese DD TT's I own.
What the OP was gently informed of is that the overhaul of a TT can extend to the Bearing housing. We can't see inside, but for a selection of individuals that do see inside, the assessment might be a good clean out, with a replacement Trust Pad and Ball for the reassembly with new lubricant.
Individuals that have seen inside, also discover operational conditions that are very much unwanted and corrective works are required. How the corrective works are produced will vary. I have become a advocate of the work undertaken to replace all sacrificial inner bearing housing parts, that remove the risks of metal on metal contact occurring during the new replays.
The use of Thermoplastics as Bushes and non-metal Balls and Thrust Pads, has been so attractive as finished design, there is no want to return to what was.
The OP as a owner of a Vintage Japanese DD TT is now aware of the Bearing Housing being very old and most likely never having undergone a oil change.
The OP also is now aware of how an investigation of the Bearing Housing followed by a service or overhaul will prove to be very good for its future use.
To receive the required support for a overhaul on a DD TT will be a hurdle to get over, if this is a adopted method. Other TT's have options for a overhaul readily available.