its a mistake in the manual dude,,i just glued my 30mm rods half way in,,no the push rod sleve is not normal heat shrink its teflon and the manual and most people say to use a hairdryer ,now i had many attempts at this and was never happy with the result so i found the best way was a lighter and do it quickly starting from the middle and working out both ways but be sure to leave it a good 10 mins before you touch it as it stays very soft for a while