I've had this issue with my NSM, i carefully remove the records, took the carraige off and put it in the start position, turned the whole unit off and then on again, it reset itself.
Having said that, there is also a philips screw which is an adjustment on the bottom of the arm that pushes the record into place to be played, you may want to adjust this too.
hope that helps.
Gra, May 2012