Direct from Champion when asked about this specific issue:
"I'll start with the fact that we have had a timing drift issue on a small percentage of mags for some time and have tried different remedies to minimize this effect. I will also emphasize that all Slick mags have timing drift by design, as the points erode timing advances and as the cam erodes timing retards, each of these must happen for the mag to remain in the area of e-gap over it's 500 hour expected service run. Champion released SL 74-20-001 (attached) in Feb 2015 because we have had excessive advanced timing drift happen on some of our mags . I have also released SB1-15 (attached) which deals with premature failure of the distributor gear finger in 4 cylinder mags and yes, some 4 cylinder mags could be impacted with both issues.
The timing drift SL does state that more than 4 degrees timing drift in 100 hours or less must be investigated and resolved (meaning warranty if it happens during our warranty period). The SB requires all distributor gears within the s/n range to be replaced, regardless as to whether they are working perfectly or not and as one option we are replacing these at the factory at no-charge, please see all possible options called out in the bulletin.
Champion did revert to the Unison design M3081 points on Sept 1, 2015 because we were never able to fully control the amount of timing drift that was happening with our M3081 design of the last few years. Any mag manufactured after Sept 1st 2015 and any M3081 points packaged dated after Sept 1st 2015 will have the "Unison" style M3081 point design incorporated. "