Sorry for starting another thread related to my transmission woes, but does anyone know why I can't get my centre viscous coupling out?

The tailhousing and drop gears are off and I thought it should just come out by hand now, but it's really really stuck.

 

Finally got the viscous coupling out tonight using a combination of levering with claw hammer + massive screwdriver and whacking both with hammers!

Really don't recommend that approach, but I was getting a bit desperate tbh...