My guess is to just replace the clip latch and/or spring; however, inspect the follower rod first for any defects.
Either way, it sounds like a simple fix you can take care of yourself. Here are the possibilties according to the US Army manual
Premature cartridge clip ejection.
Possible Source of Problem • Solution
• Worn cartridge clip detents. • Replace cartridge clip.
• Weak clip latch spring. • Replace clip latch spring.
• Worn clip latch. • Replace clip latch.
• Bent follower rod. • Replace follower rod.
• Worn follower rod forks. • Replace follower rod.
• Worn or deformed op rod catch. • Replace op rod catch.
• Worn follower arm. • Replace follower arm.
• Follower rod rubs on op rod catch. • Replace follower rod, clip latch op rod latch
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