Kumatsu PC35 MR

Hi I just bought a Kumatsu PC35 MR with about 2500 hrs. on it and started to use it and get familiar with it.I was informed it had been serviced recently. But just to make sure I toped up all the fluids, check the filters ,and blew the radiator. The first few hours it worked normal but now when I extend the arm the whole way the engine bogs a little and then if I keep working the machine stops all hydraulic functions the engine still runs but ,no arm, bucket or tracking can be done. Note I had to tighten up one of the connections to the control valve that was leaking after I did it that's when I started having problems. I rechecked the hydraulic oil level and it's ok, checked all the fuses and they were ok too. I'm thinking of two possible solutions: 1. try to bleed the hydraulic oil (if any one can tell me the procedure I'd appreciate it) I have a bobcat 753 and after replacing the hydraulic oil all I have to do is let the machine warm up and elevate the bucket then tilt it back and forward and that takes care of the bleeding. Also have a Takeuchi mini that you need to leave the hydraulic reservoir tank open and then do all the functions and that's it then you put the cap back and tighten it sealed. I'm getting me a service manual soon. 2. I'm going to check the switch under the left arm : some times the machine wont start if the lever is on the activated position (lowered down) some times it does. Some other times the lever does not fully engage and need to bring it up and down a couple of times. Also noticed that if I rev up the engine the functions start working but no in idle. If any one out there could help me I'm listening. Thank you in advance for your time. SNKMTPC096E05009774