I have the same stairs, and track. Same bare screws. Wonder if the insert was just poorly made, and did last long as it would appear this is a chronic condition. I just had my liner replaces and that is the seal for the strairs that keeps the water in the pool. Let me know if you find a place that sells the replacement. I would love to finish my new liner off by trim up the stair frame.
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Just saw the post above, and found also...thanks