Mario'sBrother wrote:

Function keys ?
are function keys in need of drivers ?
How do they get their juice ?

e.g. Do not work
under F2 is a Lock icon.
under F4 is a Moon icon
etc ...

These work
under Home/End is a screen brightness up/down
under PgDn is a keyboard light.

My T410/W32 and T420/W64 required drivers for the F keys.
I found out when I tried installing W64 on the T410 but did not load
all the files. Some F keys worked and some did not, at least until
I installed ALL of them.
Unfortunately the list at Lenovo does not specify and I don't
remember which driver files do what.
You may need to re-install all of them.
https://download.lenovo.com/eol/index.html