For the 1st question on the code upgrade. 12.2.10a has a sw advisory against it and was made unavailable on cisco site for download. It is recent code as well. The advisory doesn't really have any documented issues for the 7200 however (3600 HSSI issue mainly). You may want to look into going to 12.2.12a which is the latest revision of the 12.2 mainline code. I wouldn't recommend going to another 12.2 train code unless you are specifically looking for and need a new feature introduced in that train.
Are all ports in the 3 8 port T1s populated? Are you seeing multiple T1s flapping or just one? Anything showing up the log?
Do a 'show interface (interface)' on the flapping interface and see if you have any input errors or other errors. You may want to clear the counters and repeat this command frequently to get a baseline for how often the errors are increasing. If you're getting errors maybe look at doing a local loopback test to see if it may be the equipment. You could also move the config to another port to see if the problem follows the router interface or the circuit. Try a working good circuit on the flapping interface also. This will require some downtime and reconfiguration but is part of troubleshooting process.
How are the T1 interfaces configured that are flapping?
