issue with turning left

This may sound like a silly post but i have a problem that has been causing me fits. I have a BERVO MMM 2200kv. I use a spektrum Dx3 and an airtronics single servo.
I had same issue when running dual 2075 servos
I have my setpoints for left and right steering set to 125%. I have the extended range servo stop installed and the link in the outer servo hole in the servo arm. When i turn left it doesnt turn as sharply when it turns right. I have tried to move the servo horn to be a little left of center when i mount it with the transmitter zeroed out but that doesnt help either.Nothing appears to be binding in the steering setup, linkages, servo stop etc and - I can move the wheels further left after the transmitter is at full leftI consider myself a very experienced RC person but this is driving me nuts
ideas?