I too have a grandmother clock. My mother bought it as a remembrance of her mother when the estate was settled. It was purchased in '66 and is still running - without service -- to this date. It's a Ridgeway clock, do not know the maker of the guts. It can be finicky. When I move it to clean it may take a few days to get it running as it should, it's on carpet so that makes it a bit harder to level. But it chimes every 15 minutes and has for 50 years now.
Hope you get many years of use out of yours...
Hope you get many years of use out of yours...