Doug : "Finally, the entire system must be able to overcome the variable load of stylus drag whilst playing real records, an extremely difficult engineering problem. "
There is a name for this, it's called mechanical coupling. I think you are overstating the difficulty of achieving tight coupling, it isn't hard at all as anyone with an idler table can attest.
The difficulty has been getting a motor that runs on speed which is quiet enough to be used when tightly coupled. That difficulty is slowly being addressed through several avenues, some of which haven't reached the market yet.
There is a name for this, it's called mechanical coupling. I think you are overstating the difficulty of achieving tight coupling, it isn't hard at all as anyone with an idler table can attest.
The difficulty has been getting a motor that runs on speed which is quiet enough to be used when tightly coupled. That difficulty is slowly being addressed through several avenues, some of which haven't reached the market yet.