Ring Stinger Clone - Uncertain Values

[Rectangular]

I'm almost finished the build of my string ringer, just a couple of concerns:

I'm using the  42tm006 audio transformers from Mouser, instead of the LT44's 
http://www.mouser.com/catalog/specsheets/XC-600134.pdf
The Primary side has three leads, as does the Secondary side,  but on the Ring Stinger layout, only two leads are shown for the primary side. I'm curious as to which two leads I'm supposed to use, and which one to ignore. is the center lead a "center tap" ?

secondly, there's no value indicated for the Blend pot in the project sheet,  I was hoping someone might have that information

thanks in advance
-rec

[Rectangular]

ok, found the Blend pot value, 100kb as suspected, that just leaves the audio transformers...

[dxm1]

The PDF you linked to shows the middle leads on both sides (2 and 5) as the center tap for each winding.

[markusw]

I'm curious as to which two leads I'm supposed to use, and which one to ignore. is the center lead a "center tap" ?

Leave the middle tap unconnected. 

Markus