Also do not overlook the 'fact' the Platter is receiving side force that will add a force to the Platter Spindle.
Think of the Bearing Housing fastened into a quite thin metal as an anchor point. The Force on the Platter that is also being loaded into the Spindle will be encouraging the Bearing Housing to route force into the interface between Bearing Housing / Chassis.
Flexion is to occur and will be most amplified at the Base of the Beating Housing.
Eccentric Rotation can be occurring at the Bearing Base, that is then in a lesser degree being produced at the Spindle.
The overhang of the Platter Rim from the Spindle and Platter Mass will assist with amplifying rotations that are eccentric.
A Styli in a Groove in such an environment is going to be functioning in a way that is not allowing for it to be a optimised interface in the groove.
Bracing the Bearings Base, or Rigidly Coupling the Bearing Housing Base is a long time seen fix on TT's that have the potential to produce a flexion in the Chassis, that is at its worst when impacting detrimentally on the Bearing Housings Base.
A lot can be achieved if keeping the original Bearing Housing and producing mod's for it, most replacement bearings seen today as a commercial offering, are only a end design that utilises plagiarized DIY Designs.