GY6 Ultimate ProBld Head Kit

I have a GY6B with 57 mm stud spacing and this head slides all the way on perfectly fine until I get to my two cheaper pens in between the head and the jug and it won’t slide over those pens, it goes almost all the way on and then refuses to connect to the cylinder I’m very agitated because I know I have a 57 mm GY6B because I’ve ordered plenty of parts for this before so I’m very disappointed that this doesn’t work and I’m trying to figure out why