[Brian]

Yes, I noticed how someone had gone around it with a centre punch. Rather than welding the arm on, [which is a bit crude, particularly if you ever want to remove the arm for any reason, you could put a couple of 'scotch keys' in it. What is a scotch key you ask....if you utilise a couple of your dot punches, you could drill and tap say 1/2" deep and fit a couple of grub screws. Half of each thread is in the shaft, the other half is in the arm, That will ensure the arm stays in place, and in the future, should servicing ever need to occur, the grub screws can be removed to enable arm to come off. just a suggestion....