My John Deere GX345 has hydraulic problems. When first starting, the power steering and deck lift are noisy and slow to react. This improves some after warming up. It is important to note the transaxle/transmission works fine without any issues! The hydraulic fluid has been changed along with both hydraulic filters on a regular basis with JD Hygard low vis. I've owned the unit for about 13 years and it has less than 600 hours on it. With the price of JD parts, I hate to go through the process of elimination on changing out parts. Any help would be appreciated.