What to do if the lower leg detaches when retracting it?

It should not happen, but if you are pulling it out very quickly, it is possible. The same could apply after years of using the folding stool, as the red plastic button can soften over time. In those cases, there is no problem putting the lower leg back by pushing on both red buttons at the same time. It's the same procedure as when releasing the lower leg to wash it and then putting it back. This problem will not affect the security of sitting on the folding stool, but always ensure that the red lock button is in the correct position and is visible after extending the telescopic legs to obtain the normal seat height.