Hey guys, Bernie gives some great points especially letting down the power which I forgot to mention. Thanks Bernie
I do not have a problem working on these, the most costly issue can be that the plating on the pivots is starting to flake off. You can repivot them though. I have only repivoted but a few while refurbishing many. be very gentle with the pivots as they are easy to bend.
I wonder if the biggest “real” reason smiths are just replacing the movement is because they have not taken the time to understand how to take them completely apart and reassemble properly, possibly…… all I know is the guys around here who have retired from clock work have piles of what they called “worn out” movements, when in fact there are only 1 or 2 pivot holes worn underneath parts that have to be taken off in order to get at them. I have only found it cost effective for a customer one time to buy a new movement.
maybe my prices are too low 🙄
Dont let someones lack of initiative deter you from fixing that clock, yeh it maybe easier to throw away and buy new but that seems to be the problem in society today as we walk over piles of garbage. Using this clock to learn and become a better horologist will benefit everyone. It wont be easy, and be careful, it may be rewarding. 
William