Rudder shaft

[Turner]

The rudder shaft goes through this square metal block, the block is not tight and can be moved back and forth around the rudder shaft, is it supposed to be able to move? What is it and what purpose does it serve?

 

[Nightsky]

The rudder shaft goes through this square metal block, the block is not tight and can be moved back and forth around the rudder shaft, is it supposed to be able to move? What is it and what purpose does it serve?View attachment 66134

Without a better perspective, I'd say that block holds the rudder up. It is supposed to allow the rudder stock to rotate while preventing the rudder from dropping. There should be NO side to side or wobble movement.