Tempus Fugit Grandfather Clock Works Intermittently?

My grandmother used to have this grandfather clock in our house. It was still working after moving the clock from one city to another. It suddenly stopped on a fine day. I tried everything, but no avail, it was dead.

We moved it upstairs and the clock started ticking, with the mechanism off the hook which it should stay. After a few weeks or a month, it stopped again. I think something was stuck in the mechanism or something needs to be replaced. It has an even tick-tock and the chimes and strike are good. I don't overwind it, because that I don't want to break that clock.

P.S. The clock is about 30 years and above old. It was bought in early 1980s.

What do you suggest, repair it or place a new movement in the case?

By David