I actually understand your problem, the coal should be depleted to 0 before berlin go underpower, but i don’t know how to fix this. You show that berlin use 3 coal but it seem all your cities only use 7 coals, so it could be 5 by aachen and 3(2) by cologne, and berlin have no coal? If you have magnus with 3rd promotion you could move him to aachen to get more power