Thanks a lot for the help so far. I was running it on a job last Friday and looked it over again. I'm pretty sure I saw the two pressure switches on the front of the valve bank. Back by the pump there is a small hydraulic filter and a small valve body looking thing that has either 3 sensors or pressure switches on it. That is where the cylinders for the throttle bell crank get their oil. What role do they play in the system? I changed the dash switch a few years ago, I was just assuming that since the idle indicator light went on and off with the switch that it was still functioning, am I wrong to assume this. You guys are right though, there aren't many d series around, they're getting pretty old. I ran one for a guy 14 years ago when I started operating. When my business got to the point I could afford an excavator I kept looking for a 590 because I knew what I could do with one, the reliability they had, and how great they were on fuel. Mine is a 94 and just turned 7k and still pulls a full bucket every time. I'd love a nice 160 but I'd also love this old girl to make me money for another 7k hours lol