In a crawl space within the third floor of our 1915 house was a painted-over fan windor (semi-circle). I removed it from it's frame to strip the pain on the glass and to repaint and glaze the window. The window came out of the frame very easily. When I attempted to put the window back in the frame several hours later, it appears that the frame has shrunk, because the window no longer fits. Alternately, the window may have expanded. I did heat the glass panes with a hairdryer while stripping the old paint. However, after letting it sit for a day or two, it will still not fit in the opening.

Any ideas on what could have caused this, or more importantly, how to fix it?