Problems with Steering - Zooper Tango Twin...

Question

We bought a used Zooper Tango twin stroller to help with a nanny share that we are doing and in prep for the arrival of twins.Unfortunately, steering it is a real issue. The front wheels don't wish to turn and tend to go all cattewumpus on us. We have - we think - unlocked the wheels so that they can turn, they just don't really want to without a lot of mucsle behind it!Does anyone know what is causing the problem and have a solution?thanks.A