the spring on top should be held in by a screw and the spring is attached on to the sash usually with a nail. take this apart and try and find a spring of the same size and reinstall or go to a hardware store,local window company and ask if they have done any of these windows lately or in the near future so you can get the parts you need, they might even have them in the dumpster, and if they do have parts, take extras. Ask neibors if they have the same window, maybe their going to replace their windows and If so can you have the parts, If you give some pics on the outside of a sash we can probably help you figure out how to get the glass out and measure for new glass and reinstall since this is not the best time of the year to take a sash out and down to a glass co in mich unless you plastic the opening. Hope this helps, good luck.
