I had a broken Preh ME5A switch which would no longer correctly lock into the switched on state. Luckily this video by DIY Chris existed, which explained the issue and offered a solution. The little plate with a peg, which is responsible for the latching mechanism, broke, since the peg got worn down each time the button was pressed.

Chris provided a replacement plate to print, which worked, but sometimes the switch would skip. I made the peg a bit longer and the base plate a bit taller and wider and it no longer skips!

It could be that is is just because of the difference in resin printing and FDM printing (I used the latter), but either way this version seems a lot more reliable.

I printed my plate with a .2mm nozzle on a Bambu Lab P1P, using a raft and tree supports, with the plate standing upright (the peg sticking out horizontally). I printed six copies at once so each layer would have time to cool off without the nozzle melting it again.

You might wanna try testing the latching mechanism a few times with the bottom still removed to see if it works or gets stuck. I have found that it usually starts working better after a few clicks.

Weirdly enough, assembling everything with the switch in the off position made it so the switch wouldn't turn on anymore, even though the latching was working. I tried again with the switch in its on-position (which is harder to assemble as the switch wants to pull apart) and it worked again after. Make sure you hear the distinct, high-pitched clicking noise of the metal contacts when you put everything back together (and use a multimeter to test the contacts after).

Finally, Chris recommends cleaning the pins from any solder before opening the switch. You especially wanna make sure the two pins in the middle (the ones on the bulky side of the switch which are farther away from the back) stay connected to the black side of the switch, otherwise, if you pull them out you will have to tediously reassemble the whole switch mechanism!