Hi. I'm completely new to electric bikes, so please excuse my ignorance. I have inherited an early Specialized Levo Turbo HT which seems to have been hardly used. I have looked online for manuals and am now fairly familiar with the bike and the way it works. HOWEVER, there is a lever on the left handlebar which doesn't seem to do anything and I can't find any reference to it. The cable disappears into the bike frame and I believe I can hear something moving inside the battery compartment when I push the lever. I'm completely mistified, can anyone help?