Sounds like the ejaculator is malfunctioning!
Seriously though, you'll probably have to find pics of the assembly and make sure you have everything facing the right way. The rings can be facing the wrong way on those I think. I had an 1187 that cycled with half an o-ring, so it's probably not that. Also, with the OO buck, probably won't be the hole partially plugged. My bet is the rings ( the metal ones that fit together) are on backwards.
Good luck, hopefully you can find the problem, let us know if you do.