Kobelco SK140 lost controls

I work in the maintenance department of a company that had a guy that was our excavator expert. This gentleman has moved on and now I have to learn how to take over the tasks of fixing them when they go down.

With that being said I have a Kobelco SK140 that I have lost pilot controls along with one track. I can hit the override and get it to track but that's all. Anybody have any ideas where I could start to trouble shoot this?
Be easy on the new guy lol.

Kobelco SK140 lost controls