Stuck removing striking hammer

[Boz]

I'm servicing a very dirty striking mantle clock.  It's basic in construction but seems to have survived the ravages of the years very well, though it is totally gummed up.

I cant work out how to remove the striking hammer. I can see no pin holding the hammer on to the arbor so I assume it's pressed on. I've tried using a gear puller but I'm afraid of breaking the pushing-pin. It's almost like it's not designed to be dismantled. Before I start twisting the puller like a gorilla or whacking it with a punch, am I missing something? Maybe heat would help?

[transporter]

get two screw drivers (flat blade ) I use two car mechanic ones, place them either side of the arbor and twist them, dont try to pry them upwards youll only bend the arbor.

[Boz]

Sorry for the slow reply, I've been busy with work. Thanks, it worked!