Glad it's all working out. Please keep us posted on what happened to it. What steps you had to take to find it. May help someone else out in the future.
I was walking through the warehouse one day and saw a wooden crate that didn't look like the packaging we normally received. It had no markings on the outside. I asked around and no one knew where it came from or exactly when it arrived. We had no record of receiving it and no one had signed for any unknown items. I had someone get a crowbar and we popped the lid. Inside were four slot machines! We quickly put the lid back on and moved it to a security cage. I had someone call all the carriers that had delivered in the past week until we found someone that was missing a crate and could identify the contents. They were very pleased that we found it and contacted them. The slot machines were supposed to be delivered to a casino.
1st go to shop with copy of paperwork. Give them a chance to see what you have, does the signer work there? if so i think they will take necessary steps, if not then get manufacturer involved. Either way ATF is last resort.