Would it be possible it incorporate an hour counter for the router run hours? That way there would be some indication that the brushes need checked / replaced instead of the router dying with only 1 hour left on the finish pass on a 12 hour carve. (asking for a friend)
Would something like this https://amzn.to/3K3tCdC Placed on the AC input of the Router work?
Put an old sock over your router and the brushes will last MUCH longer. Good dust collection helps too.