replacement parts
Refers to spare or substitute parts used to replace worn or broken components in machinery, equipment, etc.
Replacement parts for this machine are no longer produced.
交換部品 is a more common synonym for 'replacement parts', while 入替え部品 is less frequent but carries the same meaning.
Compound of 入替え (irekae, 'replacement') and 部品 (buhin, 'parts').