iPhone 6S/6S Plus Screen Refurbishing Backlight Problems

Hey guys I own a shop that has been successfully refurbishing our own screens for awhile. We have been running into non stop issues with having to replace iPhone 6S/6S Plus backlights during the refurbishing process. They seem to always to get damaged in the pressing machine or the autoclave. The backlights were fine and working perfectly before refurbing. I think it has something to do with the metal backing on the backlight either retaining heat melting the diffuser layers or because of uneven pressure from the pressing machine. We have tried all different temperature/pressure settings and still no luck. Has anyone run into these issues and if so how did you correct it?