As new condition, it would be a shame to chuck it away ... and expensive at £20 for a replacement
Sheared stud pressed out in a vice with a small socket over the head
Cheese-head screw of the same thread, with the lower half of the head filed into a square
Open out the hole a little by bowing it downwards with the square tang of a file, insert the screw, then use the 1/4" drive end of a socket, which just fits over the square shank, to press the base-plate back down again which pinches the screw up tight. Repairs such as this give a level of satisfaction out of all proportion to the time and effort expended.
Refit with Waxoyl smeared over the back of the light units and threads.