@djrx: Your PW1 is certainly not using firmware 4.6.1.1 (or any other v4.x firmware branch) it is using 5.6.1.1
IIRC PW1 is also the last Kindle model that can be downgraded (without being jailbreak-ed) by the simple trick of copying older firmware bin file and forcing a reboot
before unplugging from PC, even when it is already on that latest 5.6.1.1 firmware.