unzipping the window

Took my wife's 63 valiant convert out yesterday. I lowered the top and left the window zipped in. All went well until I tried to snap on the boot and the top had not lowered far enough. Even a gentle push would not get it in the well far enough to snap on the boot. I could tell it was noticeably higher. I raised the top, unzipped the window and down it went, far enough to snap on the boot....RH