How to test digitizer

[InFerNo]

I have a problem with my PinePhone and I would like to test the digitizer.

I am using Phosh on Arch Linux ARM.

It began 2 weeks ago, when the number 6 in the top row wouldn't always register as touched, but 5 and 7 did. Now I feel like I can't touch a column from top to bottom roughly in the center. Also the "send" button in the messaging app doesn't always register, right now I can't get it to work at all while it worked 30 minutes ago.

I notice it on the lockscreen when I have to enter my PIN, when I switch/close apps in the overview, etc.

Is there a way to troubleshoot dead zones in the digitizer, and in worst case scenario, is there a replacement available?

[nas]

Any paint/drawing app will show up dead spots.

[InFerNo]

Can you recommend any fullscreen drawing applications?

[sorenfox]

I have almost this exact same issue with the digitiser.

Using the QWERTY layout, it's extremely unreliable for me to hit the Y, H, and B keys. Y usually deflects the touch over to the T, H sometimes works but sometimes presses both a G and a J, and B is the same as H except with V and N.

Needless to say this is pretty frustrating. I've tested it on my KDE CE with both Plasma and Mobian, with similar results. The glitchy patch in the digitiser also seems to be a full-height 'column', as swiping sideways in the task switcher under Phosh results in a small 'jump' as my finger passes that part of the screen.