The way to check the main bearing is to remove the outer platter and belt. Hold the sub chassis/top plate (in a TD125) with one hand, place palm on the top of the inner platter and *gently* try to rock it. The early AR "The Turntable" as well as the later XB77 model also suffered compared to the earlier XA/XB model. Any slight rocking will be clearly felt if it's an issue. The 150 didn't seem to suffer so and only early 160's had this issue too I remember, but the 125mk2 and many 126's did suffer for some reason. Having heard just how much better the AR Legand model was - main difference was a newly tooled main bearing - I think a TD125 would benefit hugely too from attention here.
All is not lost though. My favourite hypoid EP80 gear oil - available in two slight differences of viscosity I believe (in Halfords) is great for such bearings and it's also been suggested that a dab of LM grease in between the bearing sleeves helps close the gap and helps prevent rocking, although for a "wobbly" Thorens I'd suggest part filling the housing a la Linn but with gear oil (not sure if the thicker EP90 is still available) - Thorens used a high speed turbine oil I understand which is like a light viscosity version of EP80 and this lubricates the bearing tip well.
Hope this ramble makes some sense.
Tear down these walls; Cut the ties that held me
Crying out at the top of my voice; Tell me now if you can hear me