I have now serviced 10 861/1861 movements. This will be my first time with an 1866. I recently had 4 days of training on the El Primero have serviced 4 of them. It will be nice to go back to something a little simpler. I will post some stuff on the El Primero down the road, it is crazy how that thing is set up inside. Onto the 1866: This in one of my personal and favorite watches. It has an hour counter issue. If the chrono is on while winding the watch the counter advances. It also doesn’t count hours accurately while the chrono is running. Some close checking of the hour counter wheel, stop lever and hour driving pinion on top of the barrel will be needed. First the back has to come off. I recently got this Bergeon case back opener to replace my Horotec one. So far it works much better. The back came off with a suction die. The movement has been de-cased. The movement ring has two push pieces in it for the date and moon phase quick change buttons. Supplies ready for hand removal. I removed the 3 subdial hands first. next the chrono seconds hand is removed. now the hour and minute hands come of together. I advanced the date counter to a safe position and it was removed next. All the hands safely tucked away. the two dial screws are loosened, one can be seen in the center slot of the movement holder. dial is off and safely stored. The dial screws were tightened back down. If this step is missed they will likely fall out while in the cleaning machine. the upper dial support plate is absent and in its placed the components for the moon phase and date are in its place. This is what the dial side of an 1861 looks like for comparison. The dial washer, moon phase disc and date wheel are removed. the movement is flipped and the hour recorder yoke is removed. This is needed to access the click to let the mainspring down the click is accessed down through this opening. the stem is removed and the movement goes in for pre-cleaning.