Hydraulic Problem With Pilot Controls

[epd2020]

I was just reading my Cat 312BL service repair manual and it states in the first part of the hydrolic section that you must bleen the air out of the body / valve after changing the Hydrol fluid and filters. there is a simple hex nut on top of the block and you loosen that after turning off the engine and lowering the boom, and release the air. I am going to try this on my cat312 because it runs great everything fine except for i cannot turn right or left even on flat ground when its running. only when it first starts and is cold i can turn a little while driving. I also have no power climing a slight hill over 10% grade it just stops, no power in travel motors. I will check filters, hydrolic level and then will get pressure gauges, if any ideas let me know