A 56-year-old Marathon County man has pleaded no contest to charges he locked a woman in a wooden box and sexually assaulted her.  Allen Jamroz will be sentenced on convictions of second-degree sexual assault and false imprisonment and he will be sentenced in June.  He was in Marathon County court Thursday.  The victim says Jamroz asked her to help with a remodeling project in his basement, but instead she says he attacked her with a stun gun and tied her up in December 2016.  Prosecutors dropped charges of kidnapping and battery as a part of a plea deal.