er don't push them into the block they will cause problems with blocking holes etc if not now when they brake down (rust).
use a old flat blade screwdriver and hit the plug off centre this will either make the plug rotate so you can use grips or lever to get it out or go straight though so you can lever it out. rub the inside with sand paper to ensure a good seal.
then use a socket of slightly smaller diameter than new plug to tap it home making sure it goes in square. job done.
if you want to pay for the travel i'll come and do it for you free of charge
.lol.