Since this type of cargo has often been exposed to several possible contamination sources over a long period of time, it requires thorough cleaning and inspection before being accepted.
Special attention should be given to steel-tracked used units. The tracks tend to harbor a lot of mud, soil and sand and a proper cleaning sometimes require dismantling.
Movable parts such as, hatches, lids etc. as well as hydraulic and engine arrangements and fittings also needs attention to ensure cleanliness and that there are no oil leaks or excessive amounts of grease where seeds, bugs or insects can adhere.