I am not familiar with your particular derivative, I had a glance and it seems that they have done evrything possible to screw up the only thing a watchdog is supposed to do. Try removing EVERYTHING related to the watchdog and go from scratch with the SOLE intention of getting a reset. Even considering an interrupt seems to disable the reset function.

The fact that you can disable the watchdog by a single bit defeats the very purpose of a watchdog. Decent watchdogs require two consequtive very different writes to restart. This is to avoid the possibility that runanway code can trigger or disable the puppy.

Erik