Our first hamster, Charlie, got stuck in tubes twice! He was quite a big hamster, but the tubes were too small. The first time was in the awful Rotostak cage we had got (he was only in it two weeks thankfully) The vertical tubes were on the small side. He did manage to free himself eventually but looked very stressed. I bought a new cage straight away and removed the vertical tubes meanwhile.
The new cage came with some plastic tunnels to use inside the cage. It was the Savic Mickey 2XL. Which is the same size as the Hamster Heaven but has narrower bar spacing - for mice. As it was just a single tunnel I put it in the playpen. And he got wedged in that too! It was smaller than the hamster heaven tunnels it turned out. It was really stressful and we had to break it apart to get him out.
Some average sized hamsters have managed with hamster heaven tubes, but tubes on cages have been a bit of a no no for a long time now, due to hamsters getting stuck and escaping.
Hamsters come in different sizes! Now if they had attachable rat tubes, that would be better! But still best to have a cage without external tubes. In the rat tubes, they can actually turn round in them and go back the other way. With the narrow ones, they are forced to keep going in the same direction, right to the end, before they can turn round and go back again.