Do I need any special tools?
I saw one pic with an o-ring puller

I use a cut off Allen wrench.

__________________
CENSORED due to not family friendly words

Okay Ive seen this suggested in various situation and Ive tried to cut an allen wrench which is tool steel, like cutting...tool steel. Tempered, hardened and no saw will touch it, so how, really, do you cut an allen wrench? grinder perhaps? Space alien tech or dental drills? Lasers? Plasma torch?

Dremel with a cutoff wheel. Wear eye protection, use a vice.

__________________
CENSORED due to not family friendly words

I used a side grinder.

__________________
Jim

I used a masonry cutting wheel on a beat up old ryobi saw.

But a grinding wheel from grampas work shop would work.

If you don't have either of these get a grinding wheel for your power drill from a hardware store.

If you can't do that you could put it in a drill as a bit and spin it against an old school metal file and

If you cant do that rub it against a rock for a few hours.