Ok. So this is a very broad topic. There are many different types of cleaners and they all operate in different ways, are different shapes and sizes. It is important to note that it doesn’t matter what type of cleaner you have, if it has debris stuck in it, it won’t work, and if the basket is full, it also won’t work.
First of all, I will assume that your cleaner is a suction or pressure cleaner (robotic cleaners typically don’t have the same issues with getting stuck as they are operated by a program which can stop, reverse, continue etc:).
So where should you start?
Empty the basket and make sure the cleaner is free of debris!
With suction cleaners, there is usually a valve on the suction line which controls the amount of suction that is being directed through the cleaner (most suction cleaners operate best between 150 and 300L/m), try adjusting this valve to allow a little more or less suction through the cleaner and then test.
Alternatively, you can try putting a float on the cleaner, or on the hose near the cleaner, this can reduce the weight of the cleaner just enough to get it out of those tight spots.
It is also very common for suction cleaners to get stuck on slight high spots on the pool surface or on drain covers, for which a different drain cover can solve the issue.
In summary, there are so many ways that a pool cleaner can get stuck that it is near impossible to address the issue adequately in a single post.
If you keep having trouble with your cleaner getting stuck, contact me by email or phone, and I will see what I can do for your specific case.