Magnetic Chuck Question - permanent magnet not electrical

I recently bought a Covel 17H grinder. It has a 10x16" permanent magnet chuck on it that has a few issues.

The lever is very diffcult to move and the magnetism does not completely shut off. I figured maybe the link was worn or something. I took the thing apart. It had some coolant in there so I cleaned all that up, cleaned the magnet up and everything internal, and stoned both magnet and the bottom side of the top piece. The link is pretty tight on the shafts. While I had it apart with the magnet separated i noticed that the top of the chuck was still somewhat magnetic- about as much as it was when put together and in the off position. I greased it up with some grease that had graphite in it and put the whole thing back together. It is still about as it was before.

Is there a practical way to demagnetize the top? Maybe I would need to take it back apart?

I have one that is just about rebuilt that I can sell you cheap if interested. Email me at [email protected] if interested. I have rebuilt a number of these.

Do you demagnetize the top when you rebuild them? What's involved in rebuilding them? I have it cleaned up pretty good and it works, it's just that the top is magnetized. I am not ready to buy a replacement. I'd like to make do with what I have. Seems like a pretty nice chuck.