300tdi injectors

my disco started to lose power smoke and rattle (like a noisy tappet) so i decided to take the injectors out as the cars not had the best of servicing before i bought it, to cut a very long story short the 4th injector near the bulkhead actually undone from the the tip of injector, came out and left the tip in the head and would'nt budge , i took the head of and think i'll have to drill the shell of the injector out, just curious is this a common problem, i just hope when it's all done and back together it cures my knocking noise? it's deff a diesel knock not an engine knock so if this does'nt work i'll turn to the pump, oh happy days.

Not a common problem. You are very lucky. Have you tried putting back the head of the injector, tightening to break the bond and then undoing the injector?

oh yes i tried with a 4ft bar and my 20 stone behind it and i could'nt budge it, it's in there rather tight shall we say, possible knackered copper washer and 1000's miles of carbon build up may be?