Ikeda 407 Tone Arms - New or Vintage

@nandric 
there are plenty of tonearns that provide multiple or adjustable mass counterweights .

examples I have owned or set up are Kuzma 4point, sme, zeta, helius, moerch to name a few. 
 

Unfortunately many audiophiles who claim to be expert do not understand the benefits or physics behind getting the counterweight as close to pivot as possible.

Dear dover, you forget to name just one with 6 counterweight while

the expression ''multiple''  of them does not say exactly how

many are involved. The difference  is as by ''numerical quantifiers''

versus  ''universal'' which are not determinate.   

@nandric 

both the kuzma and moerch have at least 4 counterweights of different weights which are combined to optimise their mass and position. By my maths that equates to 24 combinations in each case 

the helius has 3 counterweights plus 2 small counterweights used in tandem. When you order a helius they ask you for the weight range of your cartridges to ensure optimisation.

the 6 counterweights for the Sumiko are quite crude by comparison

Versatile is perhaps a more appropriate term than universal. The tonearm closest to being universal is probably Audiocraft AC-3300/4400, which offers 4 different counterweights and 2 different sub counterweights but also various armpipes, including those specifically for SPU A and EMT TSD. And it offers adjustible oil damping. So far I have been unable to find a cartridge that doesn't perform well in this tonearm. That being said, there are some low compliance MC's that simply adore the FR-64/66 arm, like FR7, Ikeda 9, SPU and Miyabi. I assume the same goes for the later Ikeda arms.

Dear dover,  ''at least 4'' does not exist in the number theory.

This then must be your meta-mathematic (grin).