I think gently gently catchy monkey first rather than whacking with hammers.
I just pulled and swapped all 4 of mine , they had had water down the well and rust had built upon bodies and well.
you want to try to break any mechanical lock that's on the bodies by rotation first rather than trying to pull up on something that's locked in 6inches deep.
think of it as someone glued in on purpose , would you try to pull em out straight up or twist it first to break the bond then pull up.
once the injector holding claw is slackened of, I only had to back and forth(don't try to force it all one way,or the nut will undo) on the large nut holding the solenoid on (large adjustable spanner) and ratlle it back and forth a few degrees(the holding claw will only allow a few degrees movement to gradually break the hold and continued until felt slack, might be luck but all 4 came up no problem.
of course I had no seal blow by, but I would still attempt this first.
does your have signs of blow by ?black gunk in and around the injector wells?
I just coated the 4 I fitted in ceramic grease rated to 1500c so hopefully no rust and easier pull out in future(on the bodies only, not near the copper seal face or near tip)