I just picked up a used Sigma 100-300mm lens for my Canon 40D. Unfortunately the seller (not on Talk Photography) sent it in some bubblewrap in a bubble envelope, no box or additional hard outer packing. I have attached the lens and it will occassionally take pictures but will then give an error message saying there is a communication error between the lens and body and I should clean the contacts. I have removed the lens and cleaned the contacts but have the same issue repeatedly. I have contacted the seller and am awaiting a response but wondered if anyone here had received a similar error and found a cure or whether the lens is shot.
