Kobelco help needed for Hyd issue

I am new to this forum, although huge fan for long time. I have see the excellent advice given and now am in need of a little myself. I have a SK210LC YQ08-U1650 and have a hydraulic problem. The machine is stuttering with upstroke of the boom/dipper. Also, sluggish turning and walking. The unit has approx 2500hrs bought new by us. This issued started after we removed a breaker that we demo. The breaker was a factory new endeco, and it was the first and only attachment we've had on the machine. I did a full hydro service new tutela oil and filters from dealer. Still acting up. Their also seems to be a delay of sorts when we release the service Saftey handle to operate, the hydro motor seems to keep running a bit? We kinda got screwed due to the fact that we don't have a dealer in CT. The nearest dealer is in NY. I would like to try to diagnose if I can, I read a thread similar to this that was a few years old. Any advice would be greatly appreciated, Ron