We made a change to the alignment pin system in 2012, and have produced and delivered tens of thousands of the new style molds, have received glowing reviews and almost complete satisfaction.
The maximum operating temperature should be limited to 400 degrees with the absolute maximum of 450 degrees, for a maximum of 30 minutes. At 450 degrees the pins will turn a pale straw-yellow. Any temperature above this will excessively reduce the tensile strength of the aluminum block by annealing. Once this overheating occurs, the only option is to send it in for replacement.
The aluminum molds will not overheat by simply casting but can be overheated by preheating with a hot plate, torch, setting on top of the pot to heat up or immersing in molten alloy for an excessive amount of time.