Speed Box S speed question


Running a Pro-ject 5.1SE through the Speed Box S. Why do I have to play my LP's at 45 (rather than at 33) in order to get accurate playback? The 33 setting is much too slow, while the 45 is on key and pitch.
Just experimented and found out if I switch the 5.1 to the 45 pulley, the Speed Box will step down the current to play at 33 when I have the 33 button pressed, then let full power through for 45's.

Hmm. Don't know if I'm comfortable with this.
Here is what the Speed Box S manual says:

"The belt must be on the smaller part of the pulley for 50hz models and the larger part of the pulley for 60hz models".

Is this where you have it?

Speed Box S Manual
Yeah - i adjusted after talking with the NeedleDocor people. Still not sure if the SB makes any noticeable difference, and since I don't plan on spinning 45's, i might just return it and invest in a better cartridge.
Mine made a big difference.