rek001
Your question was on the standard ETA 2836/2824 if I understood it correctly.
I have a fairly large collection of ETA reps, have never had one serviced and none with any problems.
I am fully aware that a point in the future they will need servicing, but to service a non complicated movement that is working properly (especially a rep), does not make sense to me. (Unless you want to do it yourself for the sake of furthering you hobby)
In the first place, the price of a replacement movement is well under the price of a full service, keep in mind that many of us can and do swap movements in their reps, if you don't feel comfortable in doing so, maybe by the time you buy a new movement and pay someone to install it, well a service may make sense. Besides, most of us get tired of a single rep and either rotate or buy a new watch well before a service is in order.
I have a minimum of trouble with movements, probably because I tend to stay away from the problem and unproven movements.