Yea it sounds like a pump problem. It is pretty easy to check. Use a feeler gauge to measure clearance between the impeller and wear ring. I'm not sure what the spec. is for the SHO, but someone on here probably has a service manual. On the older FX HOs it should be between 0.35-0.45mm. Check it at multiple points. Also look carefully at the impeller for dents, etc., that will reduce performance.