Mag check goes "pop" 2.0

[Mcstealth]

Argh!!

Yesterday, finally,  the timing was right to go pick up the plane. I got a ride to the A/P's airport. I got situated,  and the A/P comes walking up. He stated all the work I did a few weeks ago only accomplished moving the backfire from the first click of the mag check, to the second click. 

I stood there calmly, several choice words and phrases going through my mind. 

I flew her home based on the knowledge the A/P made atleast five round trip flights to and from his work airport and home airport. 

To review: I discovered that the bottom plugs were all to one mag. I swapped the pilot side plugs, top to bottom. We did a run up, and no backfire happened. I come back 2.5 weeks later to retrieve the plane , the back fire is still there, just now it is on the second click. I remember the A/P stating that the backfire was intermittent 

My thinking is that i believe the mags are okay with the simple fact that the backfire happens only one one click of the key, not both. Also that the symptoms swapped to the second click.

Maybe a bad lead wire or loose electrode in a plug?

[LANCECASPER]

Or bad Bendix starter switch?

http://www.tcmlink.com/pdf2/583.pdf