rattliong noise coming from pulsating t shaped jets

[cberr]

I am going to add some pics as I am not sure what the part I am referring to is called, but I am helping neighbor fire up her hot tub that's been dormant/empty for about 5 years. It's inside. No leaks so far and all electronics seem to be functioning properly, but when I turn on the jet 2 (it's a balboa vs510sz control box), i hear a sort of rattling, knocking noise, like a ball or a something knocking around inside the jets. I pulled the panel from the area of suspected jets, and sure enough, the noise is coming from these "jet" fittings. spa side, they are two long narrow jets that for a t. back side they look like a rectangular horn.  PLaying with aerator knob that runs to them doesn't change anything. Is there moving parts in these that could have froze up or broke from sitting so long? SHe doesn't  recall ever hearing that noice when it was working years ago.