Will a record weight harm the motor in a direct drive turntable?

An interface where moving parts are able to touch is a one way route to changes occurring over time. The condition for the environment the parts moving are making contact in will vary. 

Inspection of conditions the parts are functioning in will range from Adequately Lubricated - No Evidence of a Lubrication that has a useful purpose - No Evidence of a Lubricant have ever been used.

Any of the conditions discovered means wear of parts is occurring when the Rotations are taking place.

Any of the conditions discovered means wear of parts is occurring at very different rates of break down and acceleration to becoming detrimental to the TT's Rotation Eccentricity, Speed Stability, as well as the Stylus function when within the Groove.

My aim as always is merely to encourage such concerns are not under the Carpet, they areas valid to be checked on a periodical basis as a Stylus Wear. 

I use a 850gm weight (HRS) with my Kuzma Stabi R table which is a relatively high mass table, especially with both “wings” installed.  The weight makes an audible difference that I prefer overall.  There may be some damping effect on the sound but it does make the overall presentation a bit more natural sounding.  I was worried a little about the weight but it is a lot less than the Kuzma outer ring (1.3 kg). Kuzma makes a couple different weights that are around 330 gms. I would never use this on my Rega P10.

The answer depends upon which particular direct drive turntable is being considered.

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/

On my Yamaha PX-2 direct drive, I am using a VEM Record Clamp which is not very heavy but has Dynamic Damping.  Seems to work great.