The crank out windows can be replaced without replacing the whole window. All my windows (crank out) have separated, just hot glue and foam tape holding them together. Mine are also only 15 months old but I did not purchase the extended warranty and they are not covered. I think the reason mine have the problem is that the outside pain is contacting the frame before the inside is contacting the frame and when you close them it wants to pull the two apart. I am in the process of glueing them back together myself (I am hoping to do it this weekend). The windows are pricey at about $300 a window.
Tim and Bev
2013 Cedar Creek 34RLSA, Magnum 2800w inverter, 560w of solar.