Cart Clicks Rapidly When Pedal Pressed

[Warbird]

Hi, I'm a new owner of a used Par Car. The cart was running fine and I stopped it using the brake pedal. When I tried to go again it did not move and just made a rapid clicking noise. I looked under the seat and there were 4 cylindrical electrical units attached to the batteries. Two of these had coils beneath them. The other two just had multiple wires attached. It was one of these units, (without the coils), that was making the loud clicking noise.

You can see I'm very new at this, but I'm not afraid of getting my hands dirty. Can someone take a guess as to what's wrong, and what my next steps should be? Thanks for any direction you can provide.