I have a John Deere 2320 with about 220 hours on it. About 20 hours ago the hydro fluid started getting milky and not pumping correctly so I changed the filter and replaced the fluid. Everything went fine until the last hour of so of usage. The engine seems reluctant to hit full RPM. I have changed oil, replaced the oil, air, and fuel filters as well as adding more hydro fluid. When I try to mow, it acts low on power, even going up a small hill presents a problem. The last symptom was the chug-chug-chug in the hydro at which point I returned to the shed. Any ideas? The hydro fluid in the glass looks like new. There are no odd noises, smells, or leaks to be found... Am I headed to the dealer's shop?