I removed the injectors tonight to clean them in the ultrasonic bath I bought and on removal the seal holder ring broke up (very brittle), some of which ended up in down in the port of the head (great). I just managed to get all bar a tiny section out but there's still a bit in there. They're very brittle so I'm sure it would break up but it's not ideal to say the least. At least it's not metal I suppose. See the section on the left. It looks big in the photo but it's actually quite small. The fourth one was fully intact. Any ideas on how to get that last bit out? and whether it's likely to be an issue? I was thinking of trying a hoover on there? I'm not even 100% sure it's gone down the head, I certainly can't see it. A warning to those removing the injectors: watch out the rings on the end can be pretty brittle.