I dont understand when you say, the PVDM has stopped forwarding traffic.
The PVDM's are used to provide DSP resources for transcoding, conference etc...
Anyway if you have physical access to the routers, the Rear panel PVDM LEDs would help to identify which PVDMs are faulty. You can also use the the show diag command to check whether it has been detected properly.
HTH, rate if it does
Narayan