My Logitech K750 is having problems…the Y J A N and 4 (on the right hand number keyboard) are simply not functioning while the others are. Is it a driver issue? Anyone have similar issues? Thanks.
Hope this is a hardware issue. Spilled any liquids on it 
My K 750 has worked flawlessly for several years. (Big help, I know.)
However, i bought an inexpensive allegedly Logitech keyboard. Keys stopped working. Dragged the Internet and found i was not alone.
Returned it to Amazon. Bought a Logitech 811 works flawlessly.
Opinion — Driver No — Keyboard busted
Assuming the keyboard used to work…
Does seem like I spilled a Coke on it! Don’t think so. 
Guess I got a 