Mx5000 keyboard - Not all the keys are responding

I had a similar problem after about 6 months of use with this combo. It didn't bother me for a long while then more keys started to go. What I did to fix it was. I took the keyboard apart and using tissue paper and rubbing alcohol I cleaned all the contact points on the thin sheet of plastic that makes it all work. Put it back together and it worked great, in fact it still works and this was over 4 years ago. I hope this helps. And remember don't be scared you can fix it.