Don,
About air gap, not a real issue with charging magnets, just note polarity and spacing between magnets. BTW, the factory position is to NEVER re-glue magnets due to the liability involved, lawyer stuff.
It is not uncommon for a charging magnet to loosen with age, often rust formed under it and popped it off. Many times the magnet will fall away harmlessly as it breaks into smaller pieces.
Charging capacity will drop off proportionally to the number of missing or weak magnets. A 15 amp system can lose a magnet and still have good output and you may never know it's gone.
As I mentioned, a flywheel that has been hammered on
or dropped
is most likely to have weak magnets, otherwise it is an extremely rare occurance for any Kohler flywheel to have weak magnets. It just has not been a problem with the Kohlers, unlike some "other" brands.
The "magnet/air gap" issue really comes into play on the breakerless/electronic ignition engines.{Magnum and Command series} The gap is critical between the magnet and the ignition module(s) on these, follow the manual closely.
Hope that clears it up? Have a great weekend