I’ll bump the thread by adding a few objective details:
The current arm is the Groovemaster III
A mk2 arm can be upgraded to the new counterweight assembly ( and arm lift ) ~ $200
The effective mass of 22g is calculated using ( iirc ) 14g headshell. Or maybe it was 15g. At any rate lighter or heavier headshells can shift the effective mass value...
disclosure- I am a dealer for AudioCreative.