I changed two controllers/transformers earlier for a friend. I was there to do six. I connected the first two and well, they blew up .
The insulation between the windings was probably non-existent.
Also... uh.. TO-263 packages are surface mount and likely require heat dissipation of some kind. There is a chance that heat sinking isn't required, but it's standard practice to at least ground the tab. (Using the package like that for quick at home projects is fine. Putting it in a production power supply like that is just silly.)
Throw the rest of those powes supplies you have directly in the bin. It's not worth the risk with those shitty transformers and that poor design. It would really suck if a failure mode sent mains voltage through what you are powering. (It needs a full teardown to say for certain though.)