A few different things can interfere with pouch emptying without causing pain. “Well formed” stools aren’t the ideal target for most J-pouchers, and they are harder to eject than the pudding/applesauce consistency that seems to work best for many. I’m guessing, though, that you’ve had formed stools for a long time and the emptying problem is something new. Even so, softer stools might work better if, for example, you’ve developed a stricture. Another possible obstacle to emptying would be pouch prolapse, best diagnosed with a defecogram. There are other, less common things to consider, too. There’s a chance of a functional problem, but your body is very experienced at pouch emptying and seems unlikely to have forgotten how.
The first home remedy I’d try is bumping up fluid intake, at least to see if the emptying problem changes or goes away when the stool is softer. I’d also schedule a pouchoscopy, mainly to look for a stricture or something unexpected.
Good luck!