I'm guessing your environment is windows?
If it isn't you can use iostat to monitor your drives, I like "iostat -cMDnxz 2". This shows the output in meg/sec and only shows the devices which are doing something. Now it doesn't show "Drive starts and stops" or "Drive idle with tape in" but if you can watch the amount of data being written and the %busy that the drive is from iostat, then you can tell if you are working your drive or not. I would think that is what you ultimately want to know...
One of the things that I've discovered with iostat is that i can tell when i've got a bad tape or drive... if the %b column sits at 100% for a long time and the drive doesn't show that it is writing anything, or very little (ie <meg/sec) then either the tape is bad, or the drive is bad. I would get another tape in there and see what it does with a backup.
Hope this helps.