I have a jd 490E excavator the boom function has very restricted hydraulic flow/power. I replaced the circuit release valve (two of them), which did not help at all.the problem was intermittent in the beginning, when boom control is used with stick control...quot;
Is it just the boom or does everything slow?
The swing arm drive has a separate pump system, ether the pump is bad or the control valves have an issue. Try the forum link below.
