OK. I was looking at one of these earlier and I'll see if I can recall it - turn the whole TT upside down with the switches at the front closest to you. You should have the circuit board in front of you but green side up so all you can see are the tracks in the PCB and the bottoms of the solder points for the components?
It should be laid out in front of you as in the 19th picture in this thread:viewtopic.php?t=29065
I'll call the edge of the PCB closest to you the bottom and the edge furthest away the top.
If so you cannot see any of the components but if you could you would have the 2 large capacitors to the right and the 3 columns of potentiometers in front of you.
The 3 points you want to use to measure with your multimeter are to the left rear of the board just above the multiple solder points for the op amps.
They are the bottom of the 3 solder points for the 3 wires to the motor and are in a rough triangle shape. If you clean around them a little and get a light at the correct angle you should see that they have slightly raised letters next to them.
The left hand solder point of the 3 is 'BL' (has the blue motor wires soldered to it - I think),
'GE' is the centre one (definitely has the 2 black wires for the motor soldered to it) and as is the apex of the triangle of solder points,
'RT' is the right hand one (and I think has the red motor wire soldered to it).
The Potentiometers are arranged in 3 columns of 3 pots to a column and in each column 16rpm is the top, 33rpm in the middle and 45rpm at the bottom closest to you.
The 3 in the left hand column are for fine tuning pitch control,
the middle column is A1 for Phase One for all 3 speeds (voltage measured across GE & RT)
the right hand column is for A2 for Phase 2 for all 3 speeds (voltage measured across GE & BL)
Or as you put them in rows - top row is 16, middle row is 33 and bottom row is 45 and for each speed
left pot is fine tuning pitch control
middle pot is A1 and for adjusting for Phase 1(voltage measured across GE & RT)
right hand pot is A2 and for adjusting Phase 2.(voltage measured across GE & BL)
When adjusting the pots to get the correct voltages going to the motor in each phase for each speed do it with a very light hand as they are very sensitive.
Everything I have described is with the PCB green side up and hopefully makes sense?