[c-nsp] Safe debug commands for ATM DSL PPPoE troubleshooting?

[P C]

We have a Cisco 7201 which takes in an ATM DS3 from the telco on which ADSL
connections running PPPoE are terminated.

At times when troubleshooting using all other methods fail, we need to debug
connection problems for an individual site or PVC.  However with the
quantity of connections on the BRAS, debugging can be dangerous at best, and
the wrong command can effectively hang the device.

Does anyone know (from experience) what debug commands are safe on a BRAS
like this, and what combination of more "unsafe" commands and debug
condition statements have you also find acceptable?

Code is 12.2SRE1 on a 7201.

Thanks!