The cause of this issue is caused by a missing or defective foam (A). The toner spill usually comes from the waste toner bottle every time it is removed.
The foam serves as a filter to prevent the toner from falling into the tray.
Check the condition of the foam located behind the waste toner bottle (WTB) and make sure it is intact.
Note: Make sure to vacuum the front of the tray to remove the toner spill.
Is the foam intact and did this resolve the issue?