No way to know if the SDS is broken, or it just does not work with your TT.
I emailed VPI based on that good suggestion here.
Check the capacitor on your motor, if it is less than .68 microfarads you need to change it for a .68. Less than that value and the SDS looks at it like it is a short.
MY Question now is how easy is it to change capacitors on a turntable motor?
I should have thought of that, the Classic has to have a capacitor changed to prevent a loud pop or to use the SDS. On the Classic it was very easy, I have never has a Townsend so don't know. I suspect it is not too hard. On the Classic the cap is in the AC line attached with wire nuts [ wire nuts ARE NOT those members given to buying $2000 ICs and $3500 PCs, but I digress]. Try to take the bottom cover [if it has one] off and see if you can see a cap. Unplugged of course.
You have to do this in order to use the Classic with the SDS, a really stunning design failure on the part of VPI in my opinion. It is not in the motor itself but wired into the AC line. The Classic is also prone to making a loud pop when turned on requiring the same capacitor to be changed. They did not inform the dealers of this problem, I had to email them to find out about it.
I had this exact problem with my Rega 25 and VPI SDS. I found that if I gently help the turntable platter gain speed (on startup) by gently turning the platter by hand--giving it a gentle shove--the SDS will drive the Rega 25. I guess the SDS doesn't have the power to overcome the inertia of the platter at startup; but once the platter is spinning, the SDS drives it without further problem. Without doing this procedure my Rega would sometimes play at a speed below 33.
I had the same problem using the SDS with my Rockport Capella II. I borrowed a 230V output SDS (as I was in Hong Kong) to power the Capella, and while it worked fine for 33, the platter would slow down and stop when I switched to 45 with the SDS. The same thing happened to the PS Audio Powerplant 300. I wrote to Walker asking whether their controller could drive the Capella, and their reply was negative, stating the Capellas motor was too big. Apparently there are turntables which the SDS is not compatible with!