Sliding door makes a ticking/clicking sound when moving?

Hi,

I have the vehicle listed above XLE model. When the left sliding door opens and closes it makes a clicking or ticking sound. It only does it when it's moving. It's been like that since I bought it. Both spool control cables on the sliding doors snapped 3 weeks apart. They were replaced and the technician looked into the clicking noise but said that nothing is wrong even though the right side does not make that sound. What could it possibly be? I already greased all the components and nothing. Please help.