I have a Spacedeck and have experienced no such problems of any kind. I was going to suggest that you make sure that the motor assembly is not touching the pillar of the stationary pod, thinking you might be introducing some type of vibration-related effect. But, you say that there is audible "noise" when the motor is plugged in separately. I have heard (or not heard) on the order of a twenty or so Nottingham motors and have not heard noise of any kind from any of these assemblies - Interspace, Spacedeck, Hyperspace, Anna, and Mentor. The fact that you say the noise transfers through your speakers is, indeed, puzzling. I wonder if it is actually an issue with tonearm leads and the sound you hear is not really related to the motor.
You will find only a small number of 'Not owners who post here. I would suggest posting on the AA board, where there are quite a few more. You might also contact a couple of the large 'Not dealers (i.e. Larry at Hollywood Sound) to see what has been their experience. I would suggest ASL, the U.S. distributor, but would wager large dollars that your attempts would yield little result. What I would strongly suggest is that you contact Tom Fletcher directly (it will cost you a U.K. phone call) because he is a great guy and will likely answer the call, personally. The number for 'Not should be on your owner's sheet. If not, e-mail me and I will provide it.
You will find only a small number of 'Not owners who post here. I would suggest posting on the AA board, where there are quite a few more. You might also contact a couple of the large 'Not dealers (i.e. Larry at Hollywood Sound) to see what has been their experience. I would suggest ASL, the U.S. distributor, but would wager large dollars that your attempts would yield little result. What I would strongly suggest is that you contact Tom Fletcher directly (it will cost you a U.K. phone call) because he is a great guy and will likely answer the call, personally. The number for 'Not should be on your owner's sheet. If not, e-mail me and I will provide it.