Emperor 400 flow rate slowing

Over the past 6 months, I've noticed that my emperor 400 hob has gone from a rushing flow to a little trickle. I've washed the media, replaced the media, thoroughly cleaned the whole filter and all parts, and I cant get the flow rate back up. Has this happened to anyone else?

Check the impeller and if it's the old version 400, then there's a lever to regulate the flow

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Already checked the impeller and cleaned it out. I haven't adjusted the flow, but I will definitely check that out.