So I screwed up..took the hydraulic fill plug off to de-pressurize the tank as I was working on a cylinder. I stopped work and left the fill plug off - it was partially covering the hole but not completely. It rained twice in the last day since I went back and noticed I left it off. I'm not sure how much rain got in. I turned on the excavator for about 10 seconds and then shut it down when I realized the plug was off. Looking for some advice on what I should do now. And yes, totally pissed at myself..