first, that little movement is the pilot shuttle on the actuator. that is normal. that is required to allow hydraulic oil to the slave side of the actuator
BTW, the VP actuator is almost bullet proof.
looking at your cable movement.....check your steering cable from the helm. they last about 15-20 years and your boat is almost double that. you should be able to take the rack off helm and disconnect the stern end and push and pull the cable with 3 fingers.
no you cant lubricate them
also, check the tiller arm to make sure that is clamped tight.
does the steering helmet and tiller arm move freely when you disconnect the helmet pin and the linkage from the helm cable and actuator? if not, you will need to pull the drive, pull the tiller arm, pull the helmet and clean out the corrosion. get new bushings and seal and re-assembly