Sony Trinitron focus adjustment

[Elbaid]

Just acquired a nice Sony Trinitron KV-25X1U 25 inch. The edges are blurry while the middle is sharp. I believe I can open the back of the TV and adjust the focus knob, but want to familiarize myself with the process before risking an electric shock.
Should I use a plastic screwdriver?
Can anyone familiar with this model tell me if there are two focus knobs allowing me to adjust the inner/outer focus independently?
Is it safe to adjust this while the set is turned on (obviously so I can actually see the adjustments as I'm making them)?

Regards

[adder]

http://elektrotanya.com/sony_kv-25x1b-chassis-be-3d.pdf/download.html

[Elbaid]

Thanks for the link