Preflight checks and post maintenance checks should be given extra attention.  Many years ago I had just bought a new Tiger while my Traveler was having an engine redone.  Preflight every other time seems to find the #1 top Spark Plug loose in the cylinder.  Tighten it up and away I go.

Several hours later in a group light heading for Crater Lake in Oregon I had the engine go suddenly rough, flame out of the air intake, and then an engine not produce all of its power.  We turned back to Christmas Valley since there was no other place to land and discovered this.

The helicoil was failing and I was treating a symptom while the problem went merrily along.

Cheers

Roscoe
Yankee-Aviation.com
513-519-7008