Frank, I'm glad to hear you have it going,We used to sell the motor w/o brushes & it is harder to adjust & doesn't seem to have the low end torque like this one.I know SV stands for special version BUT I've never seen anything from Singer explaining it.I've looked & machines before & found what the difference in they also have the 144 with SV on them.You have to put your machine side by side with another 153 & look @ every part.I think sometimes the engineers @ Singer had to look busy so they did things like this.