I just replaced both actuators which were 10 years old and were leaking. Lucky they lasted the season and only drained about 1/2 the reservoir. It was pretty straight forward to replace them EXCEPT...
My actuators were installed with the short thru hull hydraulic hose fitting (not the right angle fitting) which was all gunked up with adhesive (4200?). This meant that the hydraulic hose has to be removed on the outside of the stern. This had to be done especially on Port because the large engine exhaust hose completely blocked access to the fitting. No big deal since the hole drilled in the hull easily accommodated pulling the fitting through to the outside. However, this means you need at least a couple inches extra of tubing to be able to pull the fitting outside. Starboard side, no problem, there was a nice big loop of hose off the pump. Port... plenty of tubing... BUT it was fastened down in 3 places against the stern under the stern seat lazerette. It took me and a friend at least 45 minutes to find the tie downs (one was hiding under the rudder post), get to access them, drop the screw driver into the bilge under the thruster (forgot to tie my trusty tool recovery string to it, but dug it out miraculously with a magnet), and pull enough tubing to port to allow the actuator to pull the fitting out.
A couple of things made the work achievable: 1) don't unscrew the tubing tie downs completely. You just need a couple of turns to loosen the plastic band, then spray with WD-40 so the tubing can slide. This will let you gently tug (back and forth motion worked best) the tubing through the fasten downs to have enough to pull the fitting through to the outside of the stern, and 2) once the fittings were removed, I took them down to a great hardware store nearby, who had exact replacements for a couple of bucks. HTH, Gary