Hi guys, hope you can help

Got my engine out & in bits at the mo for clenaing painting, blah, blah, blah. Just about send the upper & lower intake manifolds off to the powdercoaters & I could do with removing the plastic inserts the injectors push into. I can prob get them out but they are very fragile & already breaking up, what i don't want to do is destroy them, getting them out & not be able to get any more. I've been to the stealers but they were'nt obvious on ETKA. I Guess what I'm asking is. Is there a knack to removing them & does anyone know if they are still available? If so what are they called or even better a part number

Thanks in anvance,
Matt.