DIY Varibright - LED

Dear Hive mind. I got a 2nd hand DIY varibright grid to explore Ansible and the meeting of monome and modular (as my older grid is not varibright it didn’t make the cut for this task)
The unlit pad seen in my photo was initially lighting but became intermittent. Now it no longer lights at all. The pad still registers in max when pressed but does not light.
I am presuming the LED is dead but presumption can be the mother of all stuff ups so I thought I should check first.
If it is a dead LED can someone please tell me what kind of LED is needed as a replacement and how difficult would that be to replace? I have some basic soldering skills.
Thanks in advance for any advice.

email with photos of the unit and the circuit board

it’ll be surface mount. original part might not be available but likely you can find something close


Thanks Brian, will do.