Just to add, forcing it out will only make it harder and will make the block longer. My stutter is mainly blocks and it sometimes can be very severe. Do I sometimes replace words? Yes, but that only refuels the stutter, so I try to avoid it as much as possible and say exactly what I mean to say. The best thing to do when facing a difficult block is to just stop talking, take a deep breath, give yourself a second or two and try to ease it out however awkwardly it may come out. As long as you're talking, doesn't matter how it sounds, is way better than a block in my opinion.