There is plenty of grease. Put it on the parts to be greased.

Put sealant on the box (see step 8)

Place the machine upright standing in the normal working position with lowered arm. The front axle will fall out if the arm is in the upper position.

Gently slip the lower part in the upper part

As the screws were loose when disassembling, I put a drop of thread locker before mounting.

Mount the guides in the correct place