:hi: Welcome. I change out the fuel lines on my 318 this winter, got it in 1990. I put a "new" mower deck on after the original one was due for it's 3rd set of spindles. It was pretty beat up. My dealer had an old deck that had never been sold, got it for $1K. Only down side is I went down to a 48 inch deck, upside is the spindle bearings had grease zerks on them.
Something else to check is your hydro site tube lines. Mine were brittle and broke last year.
Mowing season is upon us! How about a picture of that 318....?
Pete