You are looking at the fourth wheel of a chronograph manufactured within the past 20 years. This picture is from an expensive watch owned by a ClockSavant customer. It showed bizarre performance on the timegrapher including large transient changes in amplitude & rate. The close-up shows black oil on the teeth of the fourth wheel. You never place or allow oil on the teeth of train wheels, the oil results in an accumulation of dirt, oil, & metal grit & damages the teeth & the pinion it interfaces with & travels up-and-down the wheel train infecting other wheels. You only oil train pivots, not teeth. The customer states that the watch was previously serviced by the manufacturer. He remembers it acutely because he made the mistake of sending them his original box— most manufacturers will not return packaging you ship a watch to them in, even if it’s valuable. I am at a loss as to how this much oil could land on a train wheel unless someone was trying a dirty trick to cover-up (in a failed manner) an issue such as over-banking. Adding insult to injury, the movement has some manufacturer-specific parts that not available to independent watchmakers. Since the 1960’s, manufacturers have increasingly worked to limit the independent watchmaker’s access to parts. Prior to that, they pandered to watchmakers as an important part of their support network and supply chain. I can tell you that the work done in service centers today is not always quality work, I have seen some very poor workmanship at times. All the while, manufacturers limit what they will work on to a narrow range & their own branded watches. The tools & infrastructure I invest-in to service old vintage watches aren’t even on their radar & I have to maintain both vintage & new servicing infrastructure as I work on both. Their watchmaker training won’t help solve a huge swath of vintage watch challenges. Despite this, the independent watchmaker has survived & its supply chain persists with great perseverance.