The basic instructions are:

Jack the truck up safely & secure the chassis at the front with suitable blocks.

Remove both front wheels.

To remove the mast - disconnect the hoses & wiring connector plugs, support the mast from the top, remove the lower mounting brackets around each side of the back of the drive unit, then remove both front tilt ram pins ( mark these before you remove them to add refitting )

Make sure all the drive unit & brake cables / pipes are disconnected.

HPT or PPT under the front of the drive unit assembly to support it & remove the chassis securing bolts each side.

Double check everything is disconnected then drag it out the front then replace the encoded bearing.

Refitting is reversal of removal.

This is a job best tackled by two people for safety / heavy item handling reasons.

NOTE: Remember the 7FBMF quirk ref the parking brake! It wont work with a front wheel clear of the floor - many get caught out by this fact & end up looking for a non existent fault.
Both wheels need to be on the floor for the parking brake to work.