Ricoh D146 Service Manual page 361

6. Image Transfer Belt Unit [A]
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To prevent the image transfer belt unit from falling out, there is a lock mechanism.
After pulling out the image transfer belt unit fully, lift the handle [B] to release the lock,
and remove image transfer belt unit.
Locking mechanism by handle
SM 4-67 D146/D147/D148/D149/D150
Image Transfer Unit