Air in Fuel 2

[Gerry]

I have a GU with a RD28, I suspect Im getting some air into my injector lines somehow over night. when I start cold in the morning one of the injectors in really noisy it goes away once you start to drive down the road. Problem only started after I put a new set of glow plugs in. Wondering if I upset one of the injectors or injector lines, would there be fuel leaking out of the injector overnight? The other thing I noticed when I pulled the out the glow plugs 2 of them had the end bit missing, is this a problem? where does the end bit go?
Bit worried