Per Rosi's email (https://www.star.bnl.gov/HyperNews-star//protected/get/epd/599.html), there is a dead tile in the EPD (West PP02 TT04) starting on run 20127001 and still present as of run 20138025. 
Figure 1: Dead tile; West PP 2 TT 4
Mike's response (https://www.star.bnl.gov/HyperNews-star//protected/get/epd/599/2/1.html) suggested that we check a mapping pattern in order to tell if it a FEE/QT issue. Following the instructions from Mike's blog post (https://drupal.star.bnl.gov/STAR/blog/lisa/how-check-mapping-vped-patterns-step-step), I requested a pedAsPhys run (20138022) using, arbitrarily, pattern #4. Here is what it should look like:
Figure 2: Mapping pattern 4: expectations
I checked the GUI (using the "bias" setting of course) to make sure that I saw the same pattern, which I did. After taking the run and analyzing the data, here is what I see:
Figure 3: Mapping pattern 4: reality
As Mike suggests, this is either a QT or a FEE issue and "[w]hen there is an access, we can go in and change Vped and look at response on the scope. If the DC voltage is changing correctly, then it is definitely the QT. If the DC voltage is not changing correctly, then it is the FEE."