This is a followup to my original posting on the restoration of a DW-5600C with the 901 module as described at this link.
When I got the watch, it was running about 22 seconds / month fast (sorry, in my original posting I erroneously mentioned it was slow, my mistake !). I wanted it to be more accurate, ideally in the range of 0 to + 5 seconds per month, and ran into some WUS posts about there being a trimmer screw I could turn to adjust the accuracy of the module. I've had experience with regulating mechanical watches, so I was prepared for a "adjust it 20 times" trial and error approach until I finally got the accuracy I was looking for.
I turned the trimmer screw (pointed at by the red arrow) about 5 to 10 degrees clockwise. I wasn't sure it that would speed it up or slow it down, but I figured that was a good first step. To my surprise, it slowed down exactly as much as I needed. Wearing it for a full month 24/7 on my wrist, it ended up only losing 1/4 of a second. When it's not on my wrist, the watch runs about 3.5 seconds fast per month. I really got lucky !