Does it look like one of these?
http://www.turntableneedles.com/Astatic-711_p_624.html
http://www.turntableneedles.com/Astatic-422_p_2229.html
I guess a pic of what you're working with would help. I'll say that the 93T listed in the Sams for your set had an output voltage of 1.5v, so whatever winds up in there you'll want to stay pretty close to that spec.
If the current cart is 0.5 that very well could be causing your low volume issue.