Old german chime clock (80yrs+)

I inherited a beautiful, german chime clock. It keeps perfect time. The only problem is that it chimes three hours ahead of the hour. example at 1 o'clock it strikes 3 o'clock. When i first got it it was only one hour off. It also strikes 10 mins after the hour. It strikes once for the half hour, but it is also ten mins after the fact. I understand that it is not a major problem. I was going to have it looked at by an elderly man who repairs clocks, but he has had a stroke and is not able to help me for now.