Yanmar YB351 - worth saving?

[skoolboi]

My old man has a yanmar yb351 mini digger that has seen better days. The engine starts and runs really nicely, however, it has a few major issues which are making us consider scraping it before it completely gives up the ghost. It is used infrequently on a small holding, however, part of the reason it isn't used more is due to its condition, so if it was renovated it would see more use.
The first issue is that it doesn't track nicely, the sprockets are well worn and the tracks often slip. The metal tracks it is on have therefore also started to wear. In the past we have used a welder to spot metal back onto the sprockets and build them up, which has worked surprisingly well. My old man is talking about doing this again, but I've had a price to replace sprockets and get rubber tracks of about £1500, which feels like a much better option.
The other more pressing issue is a number of seals are leaking, some quite significantly. Again, I've had a price to get new ones at about £60 per seal. I'd be interested to know how difficult these are to replace.
My main concern is whether I'm over looking anything. I think I'm happy to spend around £2k repairing this digger if it means we get another 5-10 years work out of it. I'm due to start work on an extension soon and hiring something is likely to be similar money. I just don't want to spend the money and find something else obvious then breaks that kills it altogether.
I'm currently away but will add some photos when I return this weekend.
Any help or advice would be really appreciated.