I was just changing the sand on my Hayward S166T sand filter and as I was removing the sand around the assembly my hand hit the center pipe and it broke off right where it goes into the center section. Are those center pipes glued in or threaded? I can't tell by looking. Everything else about the assembly is fine -- laterals and all. I hate to buy the whole assembly but I don't see that the center pipes are sold separately. Anybody know if they are and if so who carries them or am I stuck buying an entire assembly?