Without documented receipts of maintenance history. Might be a good idea to assume it's time to do a full yearly LOF. Pull sample analysis of the fluids for the start of a new baseline with you. And most shops that can handle a full cycle of maintenance for you, will also be able to change those filters. I personally would not change the hydraulic fluid, unless theirs signs of contamination. Change the filters, and top off the fluid. And see if that helps on the noise. If it does not, then good signs of an opportunity to dive a bit deeper into the system to determine the problem. And other's with your model coach may have better recommendations then what I just suggested
And now that the sell is done. Ask the place you bought the coach, if they would send your contact info to the previous owner. Asking them to contact you so you can ask questions. Most former owner's, would not mind info sharing on the coach. (At least the gent I bought my coach from, off of consignment at Holland Motorhomes was helpful to me...) Worth a try!!
Enjoy your new coach,