Other than all the normal things to check on a 20 year old boat (Mechanical, Rigging etc) the only specific that has been an issue on some Moody 35's is the attachment of chain plates, If the sealing on the deck is suspect where the Shroud fittings go through the deck , then water can penetrate and rot the Plywood bulkhead where the chainplates attach. From the inside it is difficult to inspect as the internal Joinery covers them up. There are Articles in the technical library on this subject and one way to inspect them is to drill a small hole in the Interior Joinery and use an endiscope.
Other than that I am not aware of any specific M35 Problems other than the general issues of Buying a mid 90's boat
Not a Moody 35 but I am looking for boat sharer(s) for my Moody 346; very similar and quieter in the rear cabin as one's head is forward and not over the slapping under the transom as in the 35.
She has been mostly modernised and, if you are in the Solent area, I have a superb, and cheap, secure alongside mooring with cheap electricity.
If interested, give me a ring on 01798 813 464 for a chat.