Technics SP-10mk2 oscillations

Attention, these are not experiments to be done!
The engine must work with the platter inserted, it is not allowed to play with the engine without the platter inserted .... it would end up being damaged.

What Best-groove said.  What you observed, rays, is normal and not a good idea in practice. The servo system needs the mass of the platter in order to operate properly.  The herky jerky motion of the rotor without any mass on it is what to expect.

Without the platter, the rotor oscillates  at high frequency and amplitude while turning at 33rpm. At 78rpm, the oscillations are much less so. With the heavy platter on, oscillations disappear. No gridding noises, etc.

@rays19 The servo 'hunts' without the flywheel effect of the platter. That's why it jerks like that- and many direct drive turntables do exactly the same thing. You got good advice above!

Some manufactures state,

"damage may occur if running with plater removed"

That's exactly how people get nice vintage piece to turn it to junk quick.

Thank you @best-groove, @lewn, @atmasphere for the insightful comments, really appreciate it.

Rays, you’re not the first guy to make this mistake, so don’t feel bad about it. I hope your SP10 was not damaged. Most likely it was not if you ran it only briefly sans platter.

@lewm, the SP10 is fine! I'm relieved that it wasn't anything wrong with my motor as I initially thought. Thanks again!