i got a guitar from my grandfather and it sounds good but it is very hard to tune it
(turn the keys)
Any suggestions on how to fix it
Esp M1007
ISP Decimator
5150 III
Basson 412
Can you see the gears of the tuning machines(some are enclosed)? If so, you can try spraying with a tiny bit of WD-40.
No, never use WD40 on a guitar.

Too messy, use some light oil like 3 in 1, you can put it where you want it and not spray it all over your guitar. Closed back tuners can be oiled as well, and should be, just put a drop on the string peg and let it drip into the tuner. One drop should be all you need, wait a day or two and if it's still stuff, add another drop. Just don't use to omuch, a little oil is good, a lot is NOT great...one drop at a time, wait a day or two and work the tuners a little right after oiling. I use a toothpick, small screwdriver or a cutoff from a string change to drip just a small drop wherever I want it.
Hmmm...I wonder what this button does...