Just curious as to how old your mowers are. What year are they? Did you buy new? How many hours are on them to date? All of these were bought new. 1998 21" Ariens self-propelled....guess about 450hrs. 2000 Exmark Metro HP 48" w/15hp Kaw...438hrs. 2001(bought new in Sept of 2001) Exmark Lazer Z HP 52" w/23hp Kaw...228hrs.