I don't know if there is a mechanical problem. But it does look like the top is getting too hot. Instead of printing 1 of those cube things, try printing 4 or 5 at the same time. That will keep the nozzle from being close to the same piece the whole time. It is very possible that will print OK. If that does happen, the problem you need to fight is not over heating the piece. A couple things you could do would be turn the temperature down a little, but then also tell the Slicer to spend more time per layer. Or maybe add a fan to cool the part.