It's hard to say, according to the procedure, you need to measure the amount in the lowest one, multiply it by 1.4, this will give you the maximum acceptable amount for the other 3, then replace the ones which are over the limit.

As for the socket, the injector has got a collar that spins around the body that the socket fits, the window in the socket is there so you can hold the injector in the right position with a spanner while you tighten it, if that makes sense?