Canon Perfect Binder A1 Troubleshooting Manual page 143

2-4) Remove the Dust stopper unit. Then install the new type Dust stopper unit.
2-5) Reassemble the parts in the reverse order from step 2-4)
2-6) Check sliding failure in step 1) to see whether the sliding performance has improved.
[Countermeasure cut-in serial numbers in factory]
Perfect Binder-A1 US WVL00010
Perfect Binder-A1 EU MVM00072
Perfect Binder-C1 US EGX20504
Perfect Binder-C1 EU EGZ20524
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