If the belt isn't slipping, it could be that your machine runs like it's supposed to. I'll supply a link below to a youtube of mine rinsing on "normal" speed since it appears to be running at the proper speed.
Here's a question: Is your's a single or a double speed? It's entirely possible the clutch could be slipping on it! Come to think of it, that sounds exactly like a very real possibility. The single speed clutches are still widely available, but the double speed ones are getting a bit scarce.
With the recirculating flume, the pump may have some crap in it, or the hoses may have a buildup of fluff and other garbage in there. It just seems like kind of a whimpy flow for those washers.
One last question: Is your's the "Large Capacity" (aka Standard Capacity) or the "Extra Large Capacity" (aka a true Large Capacity) machine? Mine's a "Large Capacity" one.
Those ramp agitators sure are fun though aren't they? If you load it loosely, it'll REALLY get those clothes clean too!