It is possible to buy replacement magnets from Boyer if you email them.
Personally I think Boyer get a bum rap. They have probably sold more ignition systems than any other aftermarket provider, and many folks report they are still working after decades of service.
The real Achilles heel (on the Commando anyway) is the tails on the stator shaking about causing the wires strands to shear within the cable insulator. I modify them with a surface mount screw connector (like the early Boyers had and Pazon still have).
You can see one here (which is still available
)
Modified Boyer stator pickup plate N.T.1.a ( brand new) I carefully remove the existing troublesome cable tails, glue and then solder on a surface screw terminal block. Ferrules also provided to keep the wiring nice and tidy. £35 or equivalent...
www.accessnorton.com