Rolex Cellini dual time help please

[pmp0000]

Hi All,

I am new member, I have one question if anyone can please help me. Bought used Cellini and dont know how to set the following.

When I have crown set to position 2 the hour hand moves in 1-hour increments, but I cannot adjust the minute arm without going to position 3. I need this to adjust the difference between two time zones by 2.30 hours (reference and local time). I seem to not understand how to set the difference between the two zones by 2.30 hours. Can you please help? I can adjust the reference and local time by 1 hour increments only but not by 30 minutes. Please help.
Thanks