Michael, the QA release bail must be held up in order for the blade sub-frame to not slip out. There are springs that are supposed to hold the bail in the up position but they can become weak and/or fall out. Also the release bail could be worn so that the area that is supposed to hold the sub-frame in can no longer do it's thing. As a test for wear, use a bungee or rope to hold the bail in the upper locked position.
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