The movement is 45 years old, it could need a complete rebuild or replacement. A Hermle that old will suffer from sticky springs and worn barrels, worn bushings and gunk in the pinion leaves..
I would recommend a new movement.
The first thing I would do would be to remove the balance assembly and make a few test.
Test #1 - with a toothpick, slowly move the little fork (the part that drives the balance wheel) back and forth. At about the halfway point of its travel, the fork should snap sharply to the other side, making a sharp metalic tick. If not, you have movement trouble, what John just said. If the fork movement is consistently nice and snappy go to test #2.
Test #2 - look at the bottom of the balance frame. If you see any liquid, or dried up oil there, the balance assembly needs to be cleaned. Look up "cleaning Hermle balance assembly".
Test #3 - stick the balance assembly to a piece of 'Bluetack', or place it in a vise, in its normal (at rest) position. Then turn the balance wheel 1/2 turn and release it. The balance should rotate for 2 minutes, or more.
If a test is not good, you need to do what is necessary to make it good. The main area of 'iffeyess' with these movements is the interaction of the fork with the balance assembly. This interaction is quite complex and further study on your part may be requored 'IF' your movement can pass the above three test with flying colors ...
That type of balance wheel uses two jewels. When cleaning it, be sure not to subject it to an ultrasonic cleaner or any harsh chemicals that would cause damage. Dawn dish washing detergent and warm water works very well. Let us know how Willie's tests come out.