any way to confirm a tape is bad and how to retrieve partial data?

Hi,

NetBackup 7.01 on solaris 10

I have trouble restoring data from a tape. It keeps complaining about 

cannot open ndmp device nrst2a, error code 16 (NDMP_NO_DEVICE_ERR)

I was able to use robtest to move the tape in and out of the drive. So I suspect it's the tape itself having problems. I have two questions:

1. Is there any way to confirm a tape is indeed bad?

2. If it's bad, is there a way to retrive partial data from the tape?

Thank you!