Error 403 FORBIDDEN message

In the error log it says [25-May-2017 10:56:45 Europe/London] PHP Notice: Constant PERCH_SCHEDULE_SECRET already defined in /home/robertsd/public_html/perch/config/config.php on line 8. On line 8 I have define('PERCH_SCHEDULE_SECRET', 'some numbers - removed');

So I get the 403 FORBIDDEN message when I try and view the site. The only time I can view the pages is when I am logged into Perch Runway. How do I fix this error?

Thanks

Summary information

Perch Runway: 3.0.3, PHP: 7.1.5, MySQL: 10.0.30-MariaDB, with PDO
Server OS: Linux, litespeed
Installed apps: content (3.0.3), assets (3.0.3), categories (3.0.3), perch_blog (5.5.1), perch_forms (1.9), perch_gallery (2.8.9), perch_kraken (1.1), chirp_seo (1), perch_mailchimp (3.1)
App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_blog', 'perch_forms', 'perch_gallery', 'perch_mailchimp', 'chirp_seo', );
PERCH_LOGINPATH: /perch
PERCH_PATH: /home/robertsd/public_html/perch
PERCH_CORE: /home/robertsd/public_html/perch/core
PERCH_RESFILEPATH: /home/robertsd/public_html/perch/resources
Image manipulation: Imagick
PHP limits: Max upload 256M, Max POST 32M, Memory: 128M, Total max file upload: 32M
F1: 0c66c2e1f82f9e0b7617b2cb8270f2c7
Resource folder writeable: Yes
HTTP_HOST: robertsdesign.biz
DOCUMENT_ROOT: /home/robertsd/public_html
REQUEST_URI: /perch/core/settings/diagnostics/
SCRIPT_NAME: /perch/core/settings/diagnostics/index.php