All of a sudden I find it impossible to release the brakes.

Thank you so much for your quick response ;-)

Unfortunately there's no easy way of selecting another loco. You'll need to make a new timetable first, as described in this thread: https://psteamcommunity.yuanyoumao.com/app/750170/discussions/0/2639622942684463945/

That might be some kind of a noob question, but how do I chose this loco instead of the "green" one? As iot appears there's no option to chose one locomotive over the other, or am I blind? Would really appriciate an answer. Btw.: I really like your Class 37 Reskin. Keep up the good work!