MacDon C Series Operator's Manual page 53

Maintenance and lubrication
Chopper knives and their maintenance:
Check knife (1) condition daily!
The radial clearance between knife and bushing should not exceed
1 mm (see figure!), if it does the knife needs to be replaced.
Knives must be changed only in pairs because of their high rota-
tional speed and balance requirements.
Never operate the chopper without the covering rings of the lock
Tightness of the knife support bolts should be checked daily.
Neither the Manufacturer nor Distributor takes any responsibility for wear or
failure resulting from improper maintenance or lubrication!
52
WARNING!
Never use damaged knives!
nuts (2) of the knife support!