Diagnosis
The two-piece shaft is not separating for storage. The locking collar is not being disengaged correctly.
How to Fix It
Step 1: Remove the battery. Step 2: Locate the black plastic collar near the middle of the shaft. Step 3: Pull the collar straight back towards the rear handle (it does not twist). Step 4: While holding the collar back, twist the front half of the shaft counter-clockwise approximately 30 degrees and pull it away from the rear half.
If That Didn't Work
Debris may be jammed in the coupling. Inspect the metal coupler ends for grass or dirt. Clean thoroughly. Ensure you are pulling the collar fully rearward; it requires a firm tug. Do not twist the collar itself.
Heads Up
When reassembling, align the arrows on both shaft halves. Twist the front half clockwise until it clicks and the collar snaps forward. A misaligned shaft will not transmit power and can damage the coupler.