This is my second year with the pool and the problem just started this year. The pump is on a timer to turn on in the mornings and about 1x a week when the pump turns on the weir gets stuck and the pump starts sucking in air. The water level is right where it needs to be and I tried sanding the weir lightly on all the sides to prevent it from sticking. Any ideas what could be causing this? This is the type of weir that I have (probably not the same brand, but looks exactly the same)