Thanks Belvedere, I have the manuals but havent been able to find the page to decipher the code!
What I have figured out is: LP00-0-ACT means its in the first stack. Location of faulty circuit card (MG): 0; Location of faulty circuit card (U): 3; Location of faulty circuit card (G): 8. So this is module group 0, Unit 3, Group 8.
Then in the 'bunch of numbers' it says 1: 68 and then fourteen 0's. All the others (2-8) all give 16 0's as well. From what I can tell this must be narrowing it down to the port or lens number but I can't tell how to go further in.