I've seen that (the continuing to move when the tiller is up) so many times with encoder issues on the wp 3000 series Crown Seend to have an a big issues a couple of years ago with both encoders and wiring looms particularly on the wp3200. Checking the loom for continuity using ohms is good but even if the loom is damaged and just 1 strand still.attatched it can show as fine. I very much doubt this is an access 3 issue but would put money on it being the loom if the encoder has been swapped