These clocks usually get all but accurate with age, and I'm not even convinced they were at the time .Remember this is an electro-mechanical movement, not quartz!
While overhauling will fix major issues or wear, it will never make them work like modern ones.If accuracy matters to you, then why not go for a quartz conversion? I had it done some years ago, and been pleased with it ever since.
On the other hand, there is a nut at the back of the clock which allows for fine tuning (if I remember...), you should find more info somewhere on this forum.