Dirt Devil vacuum Release pedal not working

Question

We have a Dirt Devil bagless vacuum cleaner. To lower the upright handle, we had to press a pedal on the righ hand side of the bottom part. It would make a small "click" sound and the handle would lower to the back. Recently, a sock got stuck in the beater bar and after I pulled it out, the handle won't stay upright. It seems that the pedal won't lock it up any more. Any idea how to fix it? We'd appreciate any suggestions. The Guys