I had a T-Fal TL680250/3D digital long 4 slice toaster. After emptying the crumbs tray and dumping out some stray crumbs the lever would not stay on when I plugged it in and tested it. After removing 4 screws from the bottom of the toaster, I could not easily remove the outer shell. Using 3 butter knives I practically had to rip it apart, as three tabs on both the sides were lodged tight. I could find nothing wrong with the mechanism and the parts on the circuit board did not have any telltale burns on it. Took a toothbrush and thoroughly cleaned the contact between the electromagnet and the hook that catches the lever.
After that, lo and behold, the lever caught, and the toaster worked okay.