SME 3009 II (improved) won't balance with Shure V15 III

I'm not sure what the standard balance weight is. The one on my arm weighs 89 grams. I'm seeing heavier ones available on eBay, but I don't see any lighter ones. I'm pretty sure this is what came with the arm originally.

No signs the arm has been modified. 

So ... if I need to add weight to the headshell, am I defeating the purpose of matching this arm with this cart? I bought the arm because its very low mass was meant to pair with the V15 III, which I want to use. If I add mass to the headshell, am I not defeating the supposedly ideal match between the arm and cart?

Well ... turns out it's pretty easy to reach someone at SME. I called and they told me that -- as you suspected -- this is not the balance weight that came with the arm. They sell five/six weights and this is one of the heavier ones. It's authentic -- just not the one that would have come with the fixed-head shell version of the arm. 

I can order a lighter one -- for $200 and a four- to six-week wait. So that's lovely. 

He said not to just add weight to the headshell and use it that way. 

Maybe you can find a competent machinist (out in Rockville if you actually live in DC) who can shave some weight off that CW. Could be done while you wait in the shop.

Does anyone here know a lot about these SME arms? Even though the guy at SME tells me this is not the original weight, I'm not seeing any mention anywhere online of this arm coming with a lighter weight. I only see mentions of people buying heavier weights because the original was too light. 

FWIW: My weight is 90g. I'm not seeing any mentions online of a weight lighter than that. 

Check the Ebay listings. You can get a one for a lot less than 200 bucks!