Thanks for the tips. I just informed trains.com forums.

One more thing; in the cardboard cover there's a small manufacturer logo and I think it says O.B. or B.0. Does that ring a bell ?

Like I mentioned earlier the train is spring-operated. During many decades the spring has tired a bit and it can't pull all carriages anymore In fact the only way to get the train move is by adjusting the spring on the floor and then let it go.