Roger listed the replaceable wear plates E131890 and E131889 $36.55 each. These fit just about all of the JD balers from the 430-530 on up. IF you have ran it so long that you have a grove cut into the tension arm itself then you really SHOULD weld it. Clean it up good and preheat the area before welding it and slow cool it. IF you quick cool it you will make the arm brittle and it may crack right along your weld.
These wear plates and lacing pins are two things that need to be regularly replaced. Many times they do not and larger repairs are the result.
How often do you re-size your belts??? The outside belts usually do not stretch as much as the inner ones. So the outer belts will track different as the roll deflects a little due to the different belt lengths.