ThinkPad/ Butterfly Keyboard: Lubrication/Grease?

[DarkMark]

I just got a 701CS from e-Bay and some of the keys dont push down very well at certain angles.
Is it just wear or can I put some grease or other lubricant in between the caps an the guidance? If yes what kint of grease could I use?
I know that my old siemens keyboards are greased and have similar keys to the the butterfly keyboard, which doesn`t have the frames and proper joints.

Thanks!