Hands off! Unfortunately, not the quality as before!

I bought lately for my children more Darda cars and spare engines and am extremely disappointed by the quality. Some were broken from the outset or so stiff that they did not make the looping Darda the train. Others indicated after one day the ghost - apparently the spring was broken. That's a real shame because it was a really great toy once and the cars and engines have held for years even with frequent use.