As the iPhone 6 and 6 Plus approach their second birthday, a growing number of users are suffering from what appears to be a latent manufacturing issue that presents as a gray flickering bar at the top of the screen and a display that's unresponsive or less responsive to touch.

In a new blog post and video, repair site iFixit says a number of third-party repair outlets have seen iPhone 6 and 6 Plus models affected by the bug, which appears to be very common. STS Telecom owner Jason Villmer says he sees faulty iPhone 6 and 6 Plus models multiple times a week, while another repair tech in Louisiana sees up to 100 iPhone 6 and 6 Plus devices that don't respond well to touch.

"This issue is widespread enough that I feel like almost every iPhone 6/6+ has a touch of it (no pun intended) and are like ticking bombs just waiting to act up," says Jason Villmer, owner of STS Telecom--a board repair shop in Missouri. [...]

iFixit is calling the problem "Touch Disease," and says Apple appears to be aware of the issue based on dozens of complaints on Apple's support forum, but isn't "doing anything about it." Multiple people who brought their iPhones to Apple Stores were told that Apple doesn't recognize it as an issue and nothing could be done as their iPhones were out of warranty.

Putting pressure on the display of an affected iPhone or twisting the device appears to reverse the issue for a short period, but the gray bar returns and touch functionality grows worse and worse until the touchscreen stops functioning entirely.

Replacing the display doesn't work as the problem is said to be caused by the touchscreen controller chips soldered to the logic board of the phone, and it's possible the damage is caused by the same structural design flaw that caused the major "Bendgate" controversy.

In both the iPhone 6 and 6 Plus, the Touch IC chips connect to the logic board via an array of itty-bitty solder balls--"like a plate resting on marbles," Jessa explains. Over time, as the phone flexes or twists slightly during normal use, those solder balls crack and start to lose contact with the board. "At first, there may be no defect at all. Later you might notice that the screen is sometimes unresponsive, but it is quick to come back with a hard reset," Jessa explains. "As the crack deepens into a full separation of the chip-board bond, the periods of no touch function become more frequent."

According to iFixit, the only way to fix the problem is to replace the iPhone, replace the logic board, or replace the Touch ICs on the logic board, something Apple's in-house repair staff is not able to do. iFixit recommends users who are experiencing early symptoms of Touch Disease -- an intermittently non-functional touch screen or hints of a gray bar -- get their iPhones replaced outright if they're still under warranty.

For those without a warranty, iFixit suggests taking an affected iPhone 6 or 6 Plus to an electronics repair shop able to replace the chips. Apple doesn't approve of third-party repairs, but it may be the only solution until the problem is officially acknowledged by the company.

The iPhone 6s and iPhone 6s Plus are not affected by the same issue as Apple strengthened the body and changed the position of the Touch IC chips in those devices.