I did find these guys that overhaul brose for better durability and water proofing. If you were interested. They also have parts.
Where To Buy - eBike Motor Centre (Performance Line Bearings)
I contacted EVO Elsykler AS in Norway long time ago after contacting Serial1 who told me the motor never needed service and they knew nothing about the Brose service tool I they contacted Brose Germany which told me EVO where their partners in norway and asked if they did service Brose motors but no EVO told me they do not and do not want to.
I also contacted a company called Elife in norway which make custom ebikes with Brose engines but they told me they no longer used Brose but have changed to Bafang since Brose didn't work as expected.
Another thing is why should I pay extra to make a motor work as expected and what about warranty when original parts have been changed to unoriginal?
I did trust H-D as a reliable company so I didn't check if they had a spareparts list and also sold spareparts and that they could service the whole ebike including the motor.
I am still waiting for my bike to be finished since the shop I bought it at have to order a new motor from Brose but strip down another new bike to get spare parts like new battery, new brakes and new rear axle since Serial1 don't sell or have the parts.
You can do a test yourself and send Serial1 a mail and ask for spareparts numbers and wait for a answer if you you don't believe me.