mercruiser 3.0 destroying cap and rotor
 

I am on my 4th rotor and cap in a month.last year I switched from
points to an electroic setup. which ibeleive is a pick up mounted to
the plate where the points use to sit and I believe a magnet that slips
on the shaft. I give you this info to explain how i am on my 4th set.
after #2 i looked closer and I beleive the magnet had slipped up on the
shaft causing my problem so I pushed it down and made sure rhe rotor
sat all the way down made sure the cap was installed properly. after 2
days of running great the motor backfired as I reached my dock and when
i took the cap off the rotor key was broken and the cap is worn badly
and shows wear higher than normal as if the rotor and/or shaft went up
until it broke the key. on further inspection the rotor shaft lifts up
about 1/4" - is this normal? is this my problem . the shaft does not
seem to have any play side to side(maybe with the engine in a
differrent position it might)? Is that what I should check next or does
someone out there know the solution to my problem .?just to show you
what kind of day it was - my battery died . my bilge pump died , and my
boat has a leak , and the cap and rotor are junk again. thanks for any
help

mercruiser 3.0 destroying cap and rotor