I confirmed with Thule that they do not have replacements available for the locking knob mechanism on the Thule Easy Fold XT # TH903202. The only way to get the replacement locking knob is to purchase the whole bike rack.
The Replacement Lock Cylinder and Premium Key for Thule One-Key Systems # 1500004217 is the correct lock and key needed to replace you lock core on the bike rack if you're needing to replace the lock. view full answer...