Note also that toroidal transformers have specific mounting requirements, particularly with regard to -not- creating an electrically conductive path through the mounting hardware that forms a loop passing through the core.
Some amount of temperature increase is to be expected; the 237-2051-ND at full load will actually get quite warm, per datasheet specification. The holes in the fixture base pictured are probably there to provide ventilation/cooling for the transformer, and if the installation ended up being more cramped than the original a disruption of that cooling effect is probably happening. Note that the original most likely failed as a result of overheating also; the “thermic protection” mentioned most likely amounts to a fuse link in series with the primary that opens (permanently) if a preset temperature is reached. There’s really very little else that can go wrong with such things…
