weak jets

Hi, TFP! My motor changed its pitch this week. It is a much higher tone than it used to be. Also, it appears that only one of three jets are flowing. I know it's hard to diagnose in a forum, but I thought I'd give it a shot before going to the dreaded pool store. TIA

I've read quite a lot here on plumbing and pipes and old posts about no bubbles in spa jets, but since we have a new pool (well, old pool, but all new piping), I feel like our problems are because our pool builder didn't design it properly. I'd love your perspective. Problem: Spa jets have weak...