Mobile users click here to view diagram.
The Catera diagram was a hard one to find. Installation I am still unsure of until I get a chance to check one of these out myself. It looks like the top left pulley is the idler pulley. You should be able to rotate this to relieve tension on the belt or it might be on a track that it slides on. If it’s on a track or bracket, there should be a bolt you can loosen so it can slide to relieve tension.
I will go look for one this weekend and update the installation instructions but this should be enough to get you all started in the right direction.