You'd be better off to leave the trimpots alone. The settings don't age, unlike the (total 11) electrolytic and tantalum capacitors on the 44 year old board.
You need a scope and 2V PSU to set up the servo and Hall sensors, and pull the orange wire. If you do it wrong, you can damage the transistors and motor. It's largely a discrete analog servo and a multimeter won't cut it.
The speed adjust is on the enclosure bottom. With the pitch controls mid-position, set to a stationary strobe pattern. That can be toyed with. The TT would be happier to get some oil for the spindle motor.

Hi again
Just a quickie, I have been looking at some second hand scopes, the listings are for scopes of various MHz, such as: 10MHz, 20mMHz and 30MHz .

Would it matter which one of those types I purchased ? .

Cheers
Spike

 

It depends in what you are interested in. If you're interested in audio, and have an occasional need to see if a mcu clock is oscillating at 20MHz, then a 20MHz scope would be good for you. If you deal with much faster MCUs or you're in to radio then perhaps something higher.
Buy a modern LCD screen type not the old CRT types - you get so much more for you money with all the measurements etc. You can almost manage without a multimeter.
I have a (now discontinued) Tektronix TBS1022 at home and a much faster Isotech at work. The Tek is far better. Bandwidth isn't everything.
You can now get a 50MHz Tek https://uk.rs-online.com/web/p/oscilloscopes/2024903/ for what I paid for the 20MHz. Second hand may not always be cheaper.

 

The 20MHz-bandwith oscilloscope shows input signal at this frequency by 3dB less than it should be. With digital oscilloscopes comes it more difficult, you need look at sample rate and memory depth numbers also. For digital scopes you better get oscillocope with bandwith 5 times higher than the maximum frequency to be measured.