The Pinned-to-Pinned Rekey That Won't Turn
A property manager brings you a residential knobset removed from a rental unit. The tenant lost keys, so a previous maintenance worker attempted a rekey. He installed a new pin kit, but the plug now binds hard after about 30 degrees of rotation and will not return to the rest position without jiggling. You bench-test it with the cylinder in a vise. With the plug pulled and the pins dumped onto a tray, the springs and drivers look fine. Reassembled with the key inserted, the plug turns freely until roughly the 2 o'clock position, then locks up. The key is a worn original, cut on a 5-pin KW1 blank. You have a depth key, calipers, a pinning kit, and a plug follower. The manager wants it working today and does not want to pay for a new cylinder.
1. What is the most likely cause of the bind at a consistent rotation point, and how do you confirm it before touching the pins?
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A bind that appears at a consistent angular position rather than immediately at rest usually points to a pin hanging up on the shear line or a driver dropping into the wrong chamber, not to spring tension or a bent plug. The cleanest first check is to verify the key's bitting against the actual pin stack rather than trusting the previous worker's work.
Steps to confirm:
- Read the key with a depth key/calipers and decode all five cuts.
- Dump the pin stacks chamber by chamber onto a labeled tray, recording each bottom pin and driver.
- Compare: does each bottom pin match its cut, and is the total stack (bottom + driver) consistent with the bible depth so the shear line lands correctly?
If a bottom pin is one size off in a single chamber, the plug will often turn until that pin's cut rotates past the shear line and the driver drops or the pin binds - exactly the symptom described. A worn original key can also read short on one cut, so decode conservatively and test with a fresh cut on a code blank before finalizing.
2. The manager refuses a new cylinder. Under what conditions can you responsibly return this lockset to service, and what do you document?
Read the worked answer
You can return it only if the lock is restored to correct mechanical function with a key you control the bitting of, not just 'turning freely.'
Conditions:
- Rekey to a new bitting rather than reusing the tenant's old, worn key - the tenant's key is compromised, so the security objective (deny the lost key) is unmet if you simply make it work with the same cuts.
- Verify full function: plug rotates both directions through the full arc, returns to rest under spring tension, key inserts and withdraws smoothly, and the lock passes a pull test and operates the latch/bolt through its full travel.
- Confirm no damaged pins or springs were reused; replace any that show wear.
- Test with two freshly cut keys from the new bitting to catch a marginal cut.
Document: original symptom, findings (the mis-pinned chamber), the new bitting or key code reference, parts replaced, and the fact that the customer declined cylinder replacement. Note that the old key no longer operates the lock. Get the manager's acknowledgment that a repaired, older cylinder carries more future-failure risk than a replacement.