Thank you all, guys.
looks like That is not an easy task to trim the resistor.
I'll put it in test after Chinese New year holiday.
I uploaded the high resolution pictures to FTP, in case of someone zoom in for more detail.
Here is,https://xdevs.com/doc/Julie_Reasearch_Labs_VDR1067_VDR307_Kelvin_Varley_Voltage_Divider/
Find some pictures of DMR-105-10K from eBay, attached.