My 2001 Range Rover has a problem...

The serpentine belt tensioner bearing broke, so I recently purchased a brand new belt tensioner. When trying to put the belt back on and apply tension with the tensioner, it is incredibly hard for me to set the bolt back to where it needs to be. I have tried applying pressure with a crowbar, but it is still not enough.

Is there a secret to this, or is it a whole lot easier than I am making it?

Thank you in advance for the help...