75153 AT-ST™ Walker
The AT-ST™ Walker may come apart too easily if the ‘head’ of the model isn't pushed together securely. At page 41, step 65 of the build, you’ll see a grey shaft (part 6093527) and round plate (4211512). On page 63, step 109, the head of the Walker is attached onto these. Make sure to apply some pressure when connecting the head here to make sure everything is attached properly.
Another possible problem with the AT-ST™ Walker is that some builders use the wrong plate at page 66, step 117. At this step, you need part 4243797, a 4x4 grey plate, with 16 studs on top. It’s easy to mistake this part for 4211837, a grey plate of the same size that only has four studs along one side. Please make sure you’re using the right plate at the right step, otherwise you might not be able to complete the model.