This is not a major problem I will use the numbers you gave ie ,
strikes 10 at 1, 11 at 2 therefore at the 3 o clock position the clock will strike 12 at this point gently hold the hour hand finger and rotate from the 3 o clock anti clockwise to the 12 o clock position, if the finger comes off don't worry its just a friction (push fit) back on to the hour spindle
JOB DONE
wirecutterman (England)
May 2009