The air filter was never changed. I would guess the previous owner didn't have the proper tools or just didn't want to remove the air filter canister to replace the filter. Yes, you have to remove the whole filter cannister to open up the cap to get the old filter out. Also, I'm going to replace the u-joints on the drive shaft from the transmission to the front axle assembly...due to it is a 4WD unit. These u-joints are somewhat larger than the ones I replaced on the Mower deck drive shaft. I'm afraid these may be difficult to obtain all due to the Cub Cadet Parts don't show they are replaceable. I will remove the drive shaft over the winter months and take the u-joint to John Deere parts and see if they have the size needed. The previous owner must not have a grease gun, as he didn't grease any zerts.