dolphin pro rc

good morning, i wonder if you can help me. I had an issue with 1 of the 3 gold colored pins not making electrical contact inside the swivel device. I have replaced the short piece of wire that is connect to the vacuum, (spliced) that includes the other half of the swivel device. On start up, vacuum moves forward for a few seconds, stop, them move back a few seconds, then stop. It does not move at all after that. The transformer does not trip, power switch stays lit. Can you tell me what this mean? thank you in advance.