----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----John; I'm afraid that I don't understand the phrase "did not strap it down properly." Do you mean that one wing has the fabric fastened differently than the other wing? I would think that as long as no repair work was done on the wings or center section, you may be able to correct for a wing heavy condition by rigging. However, it does take some time to go through and check/correct the rigging.
Does your Coupe fly with the ball in the center, but just have a tendency to turn roll slowly in one direction when you let go of the control wheel?
I would do some basic checking myself. i.e. park the Coupe on fairly level pavement after checking the tire inflation to be correct. Then measure the height of each wing tip at the same point (If they are more than 1/2 inch different, you may have more trouble than you think.) Block the control wheels in a neutral position by tying/clamping them to something fairly straight about 30 inches long. Now tie a string (preferably with a plumb bob on the end) to the tail tie down ring. Take a close look at how the nose wheel is pointed. It should be straight ahead (that is why the string to use as a reference). If it is not, it can cause the aircraft to turn.
Mark the center of the trailing edge of the elevator. Now measure to the edge of each rudder. That distance should be the same (just a little less than 50 inches) If those distances from the center are not equal, the rudders may be causing the roll/turn. Now check the trailing edge of the ailerons on the inboard edge. They both should be very close to being even with the trailing edge of the center section. If one is lower than the other, the aircraft will most likely turn away from the lowest aileron. While you have the controls in this arrangement it is a good time to check the play between the ailerons. If you have more than minimal (about 1/8 inch) play, I would do as Greg indicated and remove all the play before you try to do any rigging changes.
If all the above checks out, and the aircraft still has a tendency to roll/turn, then you might try lowering (shortening the aileron push rod) on the side the Coupe rolls/turns to.
Those quick rigging checks have helped me sort out problems on several Coupes. The process in the service manual certainly works, and if there is any extra play in one or more of the controls, it is very difficult to rig the Coupe until all the play has been removed.
If you do resort to a trim tab, I would add only one tab. Make it out of soft aluminum, not Alclad. I would use about .032 and make it about 9 inches long instead of 5. One tab will do the job, and will help take any play out of the aileron control system by putting a slight pre load on them. Talk to your inspector (mech. with inspection authorization) to make sure it is OK with them to add the trim tab before you try to do it.
Good Luck
Lynn
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