Power Max bow thruster CT 80 - propeller removal

[miraculix]

The bow thruster of our Beneteau 40 has attracted quite a few barnacals during the last season. The propeller, the leg but also the entire thruster tunnel are full of the remains of those creatures. Needles to say that this has remarcably reduced the efficiency of the thruster, so the goal is to clean all this up before we go back in the water.
I removed one of the propellers but the other one will not come off because I cannot loosen the the set screw. The reason is the screw is filled with what seems to be bottom paint I guess, at least it looks like that, so the allen key is not going in there.
Any idea how to remove the material out of the screw? If not possible, how to get the propeller of?
Since it's plastik I could just use an ozillating saw and cut it in pieces, carefully to not damage the the propeller shaft, however I would prefer a destruction free method. Any ideas?

Is there any special antifouling for the thruster? The propellers are plastic.

Thanks
Christoph