What is the deficiency of your current system? Does it steer OK? Has it ever failed?
Disconnect the rudder head flange from your worm-gear steering and take the steering unit out.
Check it for wear and play.
It is almost certain to be a stainless worm gear with probably two contra-cut worm gear followers on it. (there may just be one follower on it). You can srew them off, wash them in gasoline, and inspect for wear.
Properly lubricated, they last for ever, but they are very expensive indeed. An Edson system is like $4000+.
If there is plenty of life left on them, lubricate and re-assemble.
I don't know if your unit has the facility for an emergency tiller with worm gear steering. My 1977 Union Polaris 36 does not. My own unit is similar in principle to the Metoer system in this link...
On your ship, if the emergency tiller can be deployed promptly, I simply would leave it as is. That really is enough redundancy. I do advise taping the necessary spanners on to the rudder post so that you do not need to go looking for them in an emergency. You may be short of time and looking for tools in a rudderless boat is going to make you sick at very best.
I plan to fit a Hydrovane independent rudder system in the spring to my ship. It is a self-contained steering system.
Then I can do no more.