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Here's how I replaced the bearings on a Porter Cable 890 router. There's also a video on youtube, but I've added a few tricks for people who don't have an impact wrench nor press.

1. Remove top housing (two phillips screws)
2. Remove brushes (two Torx screws)
3. Remove two screws (Torx/slotted)
4. Remove top brush/electronics assembly (I had to pry with a knife)

You now have the case and the armature. To remove the armature, you must remove the collet nut, but unfortunately, there's no way to hold the armature. The easy solution is to use an impact wrench, which I didn't have. Here's how I got around this problem:

5. Take a 2 x 4 that is slightly shorter than twice the depth of your hole saw (see next 2 steps)
6 Drill a 1 3/4 inch hole in the center of the end-grain (not the face or the edge)
7. Extend the hole saw pilot drill to the other side
8. From the opposite side, drill another 1 3/4 inch hole until it meets the first hole.
9. You should now have a 2 x 4 with a hole in the center from one end-grain to the other.
10. Split the 2 x 4 in half lengthwise.
11. Trim each piece so it fits between the armature and the case snugly. the snugger (is that a word?) the better. Might use a mallet, but remember, you're going to have to remove them later.
12. When you put the case in a vise, it will deform just enough to press against the two wood blocks and lock the armature. Obviously, you don't want to overdo this or you will deform or crack the case.
13. Remove the collet nut.
14. Press out the armature. If you don't have a press, use whatever trick you have such as a vise, clamps, or drill press.
15. Press out the bearing (its a 42 x 20 x 12 sealed 6004RS - mine was made in China - yuck). If it doesn't come out easily, heat the case and it will almost fall out (the case is aluminum which has a higher coefficient of expansion than steel).

16 Reassembly is the reverse - I'd suggest heating the case - makes installation of the bearing easy.

Hope this helps.
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