Help for MOTOR 2.2 Kw and control board optimum BF46 milling machine

[BILLYBOUM]

Thank you guys for your comments and brain storming's.
I got the motor out again and clamp it into a vise.
Eventually took some pics.
Oil seems to come from weak seals letting thru during horizontal transport.
I found one tiny wire i had to sold again on the Hall sensor on top of motor ( inside top cap )
All wires are rigid and insulating plastic of bad quality.
Observing the main control board, there are no hot points or burned points or inflated condensators, any other ideas for what to look for ?

Another question : i can't figure out what is the metallic box under the main control board ? is it a rectifier ? it is sealed ( by soldering stuff ) and written in Chinese on top of it.
I would be happy to find out that the problem is there.... who knows ?