Diagnose Internal Component Failure

What happens here

Examine the inside of the differential housing to identify the exact cause of the failure. The inspection reveals a severely failed bearing located at the back of the planetary gear system, indicated by significant play and missing rollers. Numerous metal shards and thick black sludge are present in the bottom of the housing. Furthermore, several teeth on the planetary gears are found to be chipped, likely caused by the previous owner attempting to force the tractor's movement. This extensive internal damage, stemming from lack of lubrication, signifies a major repair is needed. The owner concludes by seeking advice from experienced mechanics regarding the repair's feasibility and cost-effectiveness.

Goal: Pinpoint the precise internal damage causing the wheel to seize.