For a while now I noticed that MicroUSB plugs started to become very loose in my Android smartphone – even the slightest movement of the phone caused the plugs to slip out of the socket very easy.
First I assumed that the socket just was worn out (when charging the device nearly daily this makes more than 600 cycles of operation in two years). But when inspecting the socket more closely I realized that on the bottom of the socket obviously a cover of dust had build up. Because of this the plugs could not be inserted fully any longer. After I removed the debris thoroughly using a pin and compressed air the plugs stay in the socket again without any problems.
So if you have problems with loose MicroUSB plugs in older devices… maybe just cleaning the sockets may help.