Definitely double check the source. TU Quarterly monitoring doesn't give alerts for credit changes, only demogrpahic changes. However, when you get your new report at the 3rd month, that'll give a summary of the changes and it is possible to see the alert there.
If it is indeed your TU FICO report, then look at the details. Compare this report from the last one pulled (3 months ago or less) and compare line by line. Look at the 2nd and 3rd pages for any changes to the pos/neg reasons. Look at the Glance page. That page will show a summary of accounts. Look for any added red flags or the number of accounts iwth a negative indicator. Next look on the Accounts page. Look for any added red flags in the red flag column. Finally, if the first 3 fail, look line by line within each TL, especially in the payment history section. And be sure to look in the Collections section too. It's easy to miss stuff being in the back.
When looking through the accounts, look for any baddies that haven't updated in a while. A dormant baddie updating can cause a significant drop, though not by 70. Also note that the 70 loss can be a combination of several changes including increased util, added accounts, dropped accounts, etc., so the 70 might not be one item.
