l've been using these for over 25 years, 550 & 560, only things that wear for me are the drive belt and the rear wheels (l recently took to them with an angle grinder)....with the clutch spring, l blow them out with the compressor occasionally and use silicone spray.
Must say the 560 isn't near the quality of the old 550's, since Briggs took over the quality has fallen.....like honda, rover, masport