Microlighters

Good morning Chaps

My 582 engine was redone by the previous owner, the spark plugs , wires etc was replaced together with the mags, Sunday after i did some flying the one mag suddenly started to shudder when revving up the engine prior taking off doing the mag test.

Is this just a electrical component that suddenly fail and how do i make sure that it is the mag not something else?

Regards

Could be old fuel , I had a similar problem on the Cheetah , changed fuel , 95 octane plus oil whalla fixed leprechaun