You may have excessively worn ratchets on your extractor. Check your hand's width with mics in several places along its length. If the cause is hand wear, you will see that it is narrower at the top of the hand from wear where it engages and slips beside the ratchets. If it is tapered from wear, pick a hand width that corresponds with the width close to the bottom of the hand. If your hand is of uniform width along its length, then you likely have ratchet wear instead. If you have ratchet wear, you will need to buy a new extractor and fit (or have fitted) the edges of the ratchets to the hand by careful filing those end faces until the hand just starts to slip by each at full carry-up. Or, you can buy a new hand that is a thou or two wider than the hand you have and fit it to the ratchets by gradually stoning the inside edge of the hand only on the short section at the end where it slides beside the ratchets at full stroke.
Jack First also carries the extractors, found on the same page as the hands.
