Does anyone have this 'sticky' problem with the X52 Pro...?

Hi,I have recently bought the X52 Pro and on testing it I find that the stick 'sticks'. What I mean by this is when you have been holding a manoeuvre for a few seconds, say a turn, and you want to increase the rate of the turn, the joystick appears to have stuck on its base and the force required to move it means you end up jerking it to release it and over-turning, or at least pulling the nose all over the place. I actually took it back to the shop to get a replacement and the new one does it too! Does anyone have this issue and how did they fix it? I am thinking perhaps oiling or greasing but I would rather not...