This view of the base of the root ball shows how the fleshy young roots have followed the pot line around and become quite compacted. The plastic mesh that was wired into the pot drainage holes has roots growing through it and has almost become engulfed by the root ball.

In these pictures the tree has been placed on an upturned plastic container, allowing the roots to hang down. This allows the excess root length to be cut back easily and symmetrically around the root ball and in addition whilst teasing out old compost  allows it to fall down away from the material being worked on, keeping the root ball clear of old debris while you are working.

These pictures show the root ball after removal of old compost from the perimeter and after root pruning.

Here the root ball is being washed with a hose jet, this cleared out a lot of the old compost in a much gentler way than using the root hook or a chopstick.