A buddy of mine gave me a key puller years ago, and repaired keyboards.
YOu don't put a knife or screwdriver under them and pry.
The U-shaped metal IC extractor tool -- I think mine came with an Apple
][ RAM kit -- with the times reshaped and bent inwards ia good keycap puller.
No damage at all when done correctly. I pulled all the keys off my most
used keyboards and washed, dried and reinstalled them.
Inded. I pull the keycaps off all my classic computers and wash them when
I get the machine. They nearly always need it.
Thing is knowing how hard to pull. Most will jsut pull offo, bht there
are soem that have locking hooks that clip into the keyboard. The common
ones are the LK201 (whcih you get off nby twising each keycap as you pull
it) and the HP9100 (you have to remvoe the bezel and flip each hook with
a screwdriver).
Be careful with space bars. There's often a mecahnsim to keep them level.
In some cases you have to dismantle this first. In others, (IBM 5150
keyyboard), the easiest way to replace the space bar is to dismantle most
of the keyboard.
-tony