From time to time I heard a sound, something like a screw rolling in the right side of the cab. I thought that this might be under the upholstery in the door and I planned to remove it and check. But before that, I decided to hear closer from where sounds are coming, and my suspicion was directed to the BOSE subwoofer which is mounted under the passenger seat. After removing the seat, speaker cover and removing the speaker, I found two 2 zł coins in the resonance cavity. There had to come through the inlet channel, which is located at the left edge of passenger seat and apparently coins slipped out of the recess and fell straight into the canal during a turn maneuver. But there was something else. When i completely unscrew and shaked the resonance cavity, I found one American Cent, which probably was there from time of the original owner from USA.