The Two Links are showing that the 59L will benefit from a Savvy Individual looking at it and returning it to its optimised operation.
It does seem there is no useful lubrication witnessed and a speed regulation component will have moved and have caused Speed Stability Issues.
Add to this a Platter Spindle Bearing that is rotating off axis and this will cause issues with Speed Fluctuation for two reasons.
A Platter Spindle that is rotating off axis, in a Dry Environment id undergone a latge amount of rotations, is also highly likely to be wearing down metal parts that are Sacrificial and Softer by design. Particulate produced through wear of the softer metals and has the particulate present in a dry environment is going to cause an unwanted accelerated wear at other important interfaces. Noise being generated through grinding, which is being transferred to the Stylus is inevitable as a working condition.
Adding Weight will be a method that improves the grinding and is a further accelerant for unwanted wear at critical interfaces occurring.
Adding weight to a Serviced Platter Spindle Bearing Housing that has adequate Lubricant, as well as a Platter Spindle the has a True Axis Rotation, is unlikely to cause any issues. There is also a better safeguard to be adopted, which is for the Bearing Housing to be periodically investigated/serviced/ with any Sacrificial Parts at a critical interface that is showing signs of wear having the part exchanged as part of the service.
https://www.vinylengine.com/turntable_forum/viewtopic.php?t=137671
https://www.diyaudio.com/community/threads/denon-dp-59l-speed-control.423457/

