NK3A ProfessionalNoob

Hi there Nerfers-
A while ago I removed the AR's and locks from a stock retaliator. The priming stroke became exceptionally difficult to start after a dry-fire, but once started, usually by slamming a moving hand onto the cocking slide, the rest of the priming action would go smoothly. After non dry-fires, the prime was fine.
Recently, I increased the stock spring tension and removed dead space on the plunger. It is also important to note that, while modding this time around, the part of the plunger head that holds on the O-ring broke off. Bad news. Thankfully, Mom got a hot glue gun, which I subsequently used to reglue the O ring back on. Now, every prime is difficult to start, almost as if the blaster was already primed and one of the locks had engaged. However, there are no locks and the blaster is not primed, so that can not be the case.
I thought from checking around that it might be the o-ring jamming itself into the narrowed space at the end of the plunger tube, but the feel when trying to prime isn't like a soft, slow resistance like trying to pull something out of cold molasses. It is more like, as I said earlier, something very hard blocks the prime at the beginning.
Any ideas on what might cause this, and a fix?
Thanks,
fmmmlee.