Haha, no problem. I'm a dentist and the floss trick is something we do with small equipment in people's mouths.

The plastic bits just slot between the injector shaft and the clamping plate. They keep the plate aligned at the correct angle when sliding the injector in to place. They really aren't necessary so don't worry about them.

Any progress today?

No progress at all unfortunately! Can't get the injector split and can't see how to undo the engine mount to get the engine raised up to remove the last injector. Totally stuck now. When you split the injector did it come apart easily? I got an adjustable spanner onto it but couldn't get it to turn. Current 2007 TDV8 Vogue Buckingham Blue

No, the injector didn't come apart easily. I remember feeling that it wasn't going to turn but it did, with maximal force on it. It went all of a sudden.

Don't lose faith. Have another go at splitting it. Maybe an extension tube over the adjustable spanner handle. I know there isn't much room to work right down there.