Lever on taoster will not stay down

Question

the right side facing lever will not stay down. when i hold the lever down, there is no heat generating from the elements.  I have disassembled the unit but am not sure what i should be looking for.

The lever will only stay down for about 10 seconds then it pops back up and I have to hold down the lever with my finger to finish toasting.

t-fal 8780.40