Spare part for Micromatic room thermostat
This is the part of the Micromatic 'MICROTEMP' room thermostat keeping the lid in place that seems to break.
An M3 nut should just fit in the recess. You can adjust the 'tol' variable to fit your printer's tolerances.
See http://www.micro-matic.no/?CatId=1919&ProdNo=OJ1025
Beware: This is a spare part meant to retain the lid of a thermostat with lethal mains voltages internally. Any repairs you decide to carry out on this thermostat is purely your own decision and responsibility.