When priming time slowly gets worse instead of failing all at once, that almost always points to a small suction side air issue that’s getting gradually worse.
A few things I’d check in order:
First, pump lid and o-ring. Even if it looks fine, if it’s dry or slightly flattened it can let just enough air in to delay priming. Clean it, inspect for hairline cracks in the lid, and lube the o-ring with silicone pool lube. That alone fixes a surprising number of cases.
Second, watch the pump basket after shutdown. If the water level inside the basket slowly drops over a few minutes or hours, that tells you water is draining back toward the pool. That could be a suction side union, a valve stem o-ring, or even a check valve not sealing fully.
Third, impeller restriction. The pump can run fine once primed but still struggle to “grab” at startup if debris is partially blocking the impeller eye. With power off, pull the basket and feel inside carefully for leaves, pine needles, or grit that made it past.
Also double check water level in the pool. Even being just barely at the bottom edge of the skimmer opening can cause the pump to pull a mix of air and water during startup, which stretches priming time.
Since yours used to grab in 20 to 30 seconds and now takes a couple minutes, I’d bet on a small air leak or slow drain back rather than a failing motor. If you see bubbles returning to the pool once it’s running, that’s another clue air is entering somewhere before the pump.
One quick question, does it lose prime completely overnight, or just take longer to catch while still staying mostly full between cycles? That helps narrow it down.
