[Plugin: Joomla/Mambo To WordPress Migrator] Content Filter

Once more, I’m trying to modify your plugin with something which should be easy, but I’m getting crazy because I don’t understand why is not working.

I want to filter some content added for joomla plugins, so in your function j2wp_mig_pages I’m adding after your code

// Content Filter
$post_content = str_replace('<hr id="system-readmore" />',"<!--more-->",$post_content);
$post_content = str_replace('<hr id="system-readmore"/>',"<!--more-->",$post_content);

some others filters

$post_content = str_replace('<p>?</p>','',$post_content);
$post_content = str_replace('{youtube}','<a href="',$post_content);
$post_content = str_replace('{/youtube}','" target="_blank" >Youtube</a> ',$post_content);
$loadposition = array('{loadposition user1}','{loadposition user2}','{loadposition user3}','{loadposition user4}',
    '{loadposition user5}','{loadposition user6}','{loadposition user7}','{loadposition user8}','{loadposition user9}');
$post_content = str_replace($loadposition,'',$post_content);

but they aren’t doing anything.

Do you have any idea of what could be the reason?