@chungjh
I wouldn’t be on scared to change your arm. The biggest thing is getting the pivot to spindle correct with your existing arm board, or get another from SOTA as/if necessary.
Then, balancing the new arm with the suspended sub-assembly using the correct amount of lead shot weight.
lol, I know that sounds like a lot, but really, it isn’t so hard, and you will quickly understand how the SOTA works by doing this yourself. That is how I learned, by simply doing it. If you need instruction on this set-up, they can probably be found on-line, or, again, I’m sure SOTA would be willing to email you a copy.