8011 hydroulic is suddenly became slow?

[bristol]

Hi,
My 8011 Hydroulic is suddenly became slow and takes a very high RPM to get the empty bucket raised!
Hydroulic oil is ok . Could that be the hydroulic filter? Or pump?
It is easy to have the hydroulic filter changed?
Thanks in advance

 

[brenten5]

On the left hand side of the tractor under the cab is a gauze type filter held in by a wire like clip over a cap, pull it out and check its not blocked.