Haven"t had the delamination in the tail problem that Ed de Chazal has had, but our birds in general seem to have tail problems.  I've replaced the left outboard elevator hinge due to wear the symptom of which was a buzzing sound.  Had to replace the elevator fork- rod end control junction due to vibration wear.  The hole in the elevator fork for the bolt (that ties it to the control rod end bearing)  itself seems to elongate, the aluminum fork is too soft.  I'm now using an AN 5 bolt and rod end bearing with steel inserts across the aluminum control fork.. We'll see...
    Another subject:  Champion vs Autolite Massive Plugs...I promised to get the plug number on the Autolites that matched the Champion REM 40 E plugs.  It's Autolite UREM 40 E , the recommended plug for a Lyc 320 engine.  At altitude (8000 to 12000) the engine is notably smoother.  I may have had other problems, but since the plug change they have gone away.  This is from an old time A&E who has overhauled aircraft for 40 plus years and had taught engines for 27.(not me).   Don Skeele 320J  235/320 with 650 hours..