question about starters

[Trevor Irwin]

The starter is a Bosch 108 072 off a '90 100. The plastic gear track had
disintegrated: nothing surprising here. My real question is this: when I
got it apart, I saw that one of the magnets (on the inside wall of the
housing) had a piece broken off. The magnets are about 4cm long and this
broken off piece is about 8mm. It also turns out that one of the other
magnets is cracked down the center, but it is still firmly held in place.
Now, it is quite possible that I broke the magnets while I was fooling
around, but I am not too sure. Anyway, question 1: anyone know where you
can get replacements on these magnets. question 2: anyone have any sort of
experience with this sort of thing? It seems to me that the starter should
still work even if the magnets are cracked, as long as they are still
firmly in place. Any thoughts?

TIA
Trevor