A new, modified PF encoder sensor for has been introduced. This encoder sensor performs exactly in the same way but is not compatible with the old models because the shape of the mounting part is different.
This new PF encoder sensor is premounted by default on the following models:
| Model | Serial |
| XPJ-1641SR | JF6U002554 or higher |
| XPJ-1682SR | JE6U001553 or higher |
| XPJ-1682WR | JN6U001501 or higher |
| XPJ-1642WR | JX6U000058 or higher |
|
NOTE: |
Since the sensor is different in shape, it has an impact on the mounting and the orientation of the encoder-scale disc. This is because the "emitter" and "receiver" inside the sensor-assembly have been inverted. A general rule of thumb is that the "emulsion side" (the "printed" side) of the encoder disk should always be nearest to the "receiver" side of the encoder sensor to obtain the best possible encoder signal quality:
| Old | New | |
| Code | DG-49252 | DH-40770 |
| Name | PF Encoder Assy | PF Encoder Assy |
| Picture |  |
 |
| Note | - | This encoder sensor is connected to a different cable: DH-40769 - PF Encoder Relay Cable Assy |
| Models | XPJ-1641SR, XPJ-1682SR, XPJ-1682WR, XPJ-1642WR | |
When the "emulsion-side" (printed side) of the encoder-disc is not located on the "receiver" side of the PF encoder signal, it may possibly trigger random feed-related issues or worst-case PF encoder errors.