Mike,
Not being familiar with this model I would not normally comment on your post, but I take it that it is a Yale pedestrian truck, check your battery is fully charged with no faulty cells. Switch your truck on and check you have power to your line contractor and also to the output side. These contractors have a sensing circuit as well as a contact pull in winding and they do go wrong. I'm just thinking Yale will build most of there MP trucks on similar lines and therefore it stands to reason that the usual problems one encounters will be the same through out the range.