Problem solved, at least this one. There was something rubbing on the back of the motor drum. To get access to the spooling control bd mounting points when I replaced the caps, I needed to losen the ac input transformer thing attached via screws to the metal wall behind the motor. I must of switched the screws around...one shorter than the other. Backing one out a bit stopped the rub. I figured this out after removing the brake assembly and motor as per studer service manual. When I spun the removed motor, there were no sounds. Phew !