Parts for over 70 brands of shredders can be ordered online from REA Business Equipment as of 2015. The websites of the specific shredder brand are another source of parts. EBay has parts for many different shredders.
Knowing the model number of the shredder makes it easier to narrow the search. The user manuals that come with shredders have the model numbers, but these manuals do not always have a parts list. Providing the model number to an online parts seller gets a list of available parts, along with pictures for identification purposes. Gears, switches and blades are common shredder repair parts.