Output Flange won't move!!

Hi, I'm slap bang in the middle of trying to replace the transfer box rear output oil seal. I've removed the prop shaft and 30mm securing nut from the flange together with the fiber washer.

I was under the impression that the flange should simply fall off and I could go about the rest of my day - sods law, the thing wont f'in move!!

Is there something I'm missing? I cant see any more retaining hardware but it seems to be jammed?

Any advice would be most appreciated.

Cheers,
John

with a bit of force it came off lol