Adventures in newer (optical) pc steering wheel hacking
For G25 / G27 Old Version Driving Force GT Steering Wheels Systems Spare Parts Steering Wheel Optical Encoder 60 Slot|Replacement Parts & Accessories| - AliExpress
Logitech G27 off center (a few degrees). Possible fix? | Reiza Studios Forum
30 Slot Steering Wheel Optical Encoder for Logitech G27 / new Driving Force GT | eBay
coopertom on Twitter: "I found the culprit! A cracked optical encoder disc. This is why my Logitech g27 steering wheel is losing calibration http://t.co/Kvpyejyf3e" / Twitter
Spread the Word - G25/G27 optical encoder by TheAnimaster on DeviantArt