1/16" re-centering isn't very much, particularly in the flaps. Is there *any* possibility that you're chasing slop in the linkages/servo? I've watched flyers chasing centering problems time and time again, only to discover (when you sit down and physically try moving the flaps w/out the radio) that there is enough slop in the linkages to account for up to 1/8' of 'centering' problems. Slop comes from wear in the control horns for the controlled surfaces, the control arm on the servo itself, slight movement of the servo under stress (my favorite), or just badly leveraged linkages (particularly flaps). Put everything in it's normal position, and try wiggling the control surface. Most planes I have seen that are working on 'old' setups (been flying for a month or two) have developed slop from a combination of these things. Very few are rock solid. Flaps in particular present the problem.
may not be the case, but I'd check it out to make sure you're not chasing a ghost! RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]