No-contact IR thermometer trigger

So, I have this non-contact IR thermometer from China that broke after about the fifth time I used it. I opened it up, and the trigger mechanism broke, which was quite obviously because of a horrible design decision. So I decided to make an improvement.
Dear nondescript manufacturer, please feel free to use this. I insist.
Uses less than 1g of filament and is done in less than 10 minutes.