You really ought to use a pneumatic hammer to get the old ones out. To put the new ones in, you really ought to have the tool made for that purpose. If I did not have those, I wouldn't do it. A torch may also come in handy with the removal of the old ones, as they can be quite stubborn.
"...rationality of thought imposes a limit on a person's concept of his relation to the cosmos." -Nash
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