Good pick for portability but note the Coast Rider has a upright seat and limited recline, which can be tough for a 6-month-old on longer stretches. For under $200, the Summer 3Dlite or Kolcraft Cloud Plus are easier all-rounders with good recline and quick folds; the gb Pockit is ultra-compact for planes but bumpier and less cushy. Whatever you choose, practice the fold at home and lock the front wheels before collapsing to avoid that airport jam.
That model can be picky sometimes. Mine started grinding like that after a week, turned out the blade assembly wasn't seated right. I took it apart, cleaned everything super well, even used a bit of food-grade oil on the moving parts – careful not to overdo it though. Put it back together and bam, quiet as new.
If that doesn't work, it might be a defect from the factory. Worth a shot before sending it back. Works great now.