Mag Pump Impeller Life?

Alright, I did a quick search on this topic, but couldn't find anything direct on this subject.

What is the average life on a mag pump impeller? Not necessarily due to deposit build up, but due to demagnetization.

I have a Mag12 that seems to slowing down lately. I bought the set up used, but the build date on the pump is about 3 yrs old. Knowing that computer hard drives can demagnetize after 3 years and that the mag impeller operates by virtue of the non-energized magnet on the shaft, I figure there must be an expected life due to demagnetization of the impeller magnet.

I have taken my pump apart and cleaned the impeller and housing, and while that helped, it didn't completely restore the flow. Thought I'd ask this question before I went off and bought a new impeller, thanks.

 

Nobody? Surely there's a pump guru around here. Either that or an E&M guy.

 

If it has to do with demagnetization of a magnetic material, you could just swipe it past another magnet yourself to remagnetize it.

 

I considered that, just not sure if I have a magnet strong enough to be effective.