Dugena Mechanical starts and stops suddenly

[mikecj]

Everyone,

I just bought an old Dugena (circa 1958) at an estate sale. It has an EB 90 movement. The watch runs but exhibits the following characteristics.

1. After winding, the hands will not move for about 10 minutes and then they start keeping time. The hands are friction fit but don't seem to have any 'slop'.

2. The balance will stop from time to time.

3. When turned on various axis, the balance will visibly speed up or slow down depending upon its position.

Any thoughts? I have a feeling she needs to be cleaned and oiled. 

thanks,

MikeCJ

[watchweasol]

From your description it sounds like a prime candidate for service

[Klassiker]

Likely to have more than one cause, but cleaning and lubricating is a good place to start. Take plenty of photographs during the disassembly and inspect everything for wear after cleaning.

[handwound]

1. That the hands don't move while the movement is running could be caused by the cannon pinion if it is too loose. 

2. Like @Klassiker said the movement maybe just needs to be cleaned and lubricated. With time the lubricants turn into abrasives that create friction which stops the train of wheels from spin freely, so not enough energy is transfered to the balance, what causes it to stop. 

3. Maybe also just a cause of old lubricants, so try to service it first. Other possible causes could be the balance staff it it is worn. Inspect if the tips are pointed as they should be or if they have become flat. If everythink looks fine try to install the balance without the pallet fork to the movement. Gently give it a spin by using an air blower and observe if the balance moves freely. If it does, the problem probably lies somewhere else.