Hi Phillip

We also had the same problem with insufficient slots in the 3494 library
and the manual states if you require extra slots who should use the move
media command as by using the checkout ADSM loses track where your live 
data is. Its a more efficient command to use if you require extra slots.
Its in the Admin Manual look under move media.
This could be one of the reasons you are getting the problem with
scratch carts that ADSM requires thats not in the Library. 
I hope this will help you.

Thks Sean