Go ahead and try lubricating - you have nothing to lose.
About 5 years ago on passage from Israel to Kastellorizo-Greece my rudder was almost seized. It took a lot of effort to steer but we made it (luckily we were 4 on board- we had to switch every hour or so).
When I found out that replacing the bearing at that time was out of the question for various reasons, I lubricated the rudder lower bearing and continued on sailing. Have not replaced the bearing, and so far it has been working perfectly.
The way I did it:
Loosen the steel band of the rudder stock sleeve
Use WD40 can with the red thin tube - insert the tube between rudder stock and sleeve and spray generously.
Steer wheel from side to side several times
Repeat with WD40
Wait several hours.
Test - if still stiff, repeat.
It took me 3 times over 2 days to release it completely, but as said this was a very severe case, and since then the wheel has been very smooth.
If you do change the bearing - do not use the same bearing as the original - there are better alternatives (by Jeffa for example, I believe Bavaria also switched from this bearing on later years)