The problem as I see it is that the plastic of the key tops developes some friction with the keys socket and it does not get depressed easily.... I have cleaned the plastic of both with alcohol and also used vaseline to reduce friction and there is no difference. The problem is that the keys seem to get deformed in some way and develope massive friction and there is nothing I can do about it. Sadly the only other keyboard that has this problem is my old original MS Natural keyboard - the original all White Natural model - its keys have become hard to press too - not usable. As you like this keyboard I will give it to you for FREE but you will have to collect it. I also have the second model of the Natural - the MM one which I still use and like a lot.

Be careful about using Alcohol on membranes and rubbers as I understand Alcohol hardens these materials and it can crumble away. Correct me if this info is wrong.