Mags, like many less expensive pumps (including Eheim) are basically just large versions of a powerhead. Some are better than others with features like ceramic shafts, and more impeller paddles, but they all wear out over time and regular cleaning/maintenance are critical to keep them from failing.

I agree the Eheim is superior to a MAG, and a MAG12+ is better than a MAG12-, but .....

If you want a dependable, last forever pump, get an IWAKI, Blueline, PanWorld style pump. You will probably pay close to 2x for the same GPH, but cost and hassle will be far less over a 5+ year period of time.

I have 10 pumps on my system including a PanWorld 30, 40, 50, 100, 200, and MAG12s ... I used to have some MAG5/7s but they have all been tossed into the trashcan, and my Eheims are kept around in case of an emergency. When time/$s permit, the MAG12s will be history.