The Dewalt 777 brushless electric drill, which is terrible to watch, works well in a test run.
The outer shell is covered with a thick layer of hard glue, the gearbox lubricating oil has dried up, the gap is large, and the chuck is worn through.
This time, the most time was spent cleaning the remaining glue on the casing, completely disassembling the gearbox, relubricating, replacing the new chuck, and adding grease to the motor bearings.
Replace the battery with a new cell.
In the end, the functions were fully restored, the power was strong, and it could fight for another ten years.