See the bottom of this thread:
http://www.czfirearms.us/index.php?topic=85247.msg648420#msg648420
You're in good hands.
Yup, that was me with the same issue.
They had a bad batch of springs that got used in one of the early runs/batches. Mine got to the point where I could slap it with my hand and it would collapse.
I simply contacted Sven via email and he got a new stock sent out to me with a shipping label within the box so I could just drop the problematic stock in the same box, swap out shipping labels, and ship it back.
Manticore will take of you. My replacement has a couple thousand rounds on it with no issues. I am mostly pleased with how it was handled and am happy with my replacement.
EDIT: I guess Sven was typing at the same time as me and beat me...