see if you can cut a slot in the head first.i would think a screwdriver would get in there easier than needle nose pliers.make the slot tight.you could even use a ratchet with the proper slot extension.can you put some fluid to loosen it up prior?

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'95 s500 (bought for wife but can't bear to share!!!) 125kms
'92 legend 180kms
'88 tbirdturbo(fantastic car-only regular maint.)120kms
'87 mustang gt(gone)
'86 tbirdturbo(gone)
'85 mustang gt(gone-but not forgotten)