JLG 600S Operation And Safety Manual page 148

SECTION 7 - GENERAL SPECIFICATIONS & OPERATOR MAINTENANCE
4. Hydraulic Charge Filter
Interval - Change after first 50 hrs. and every 6 months or
300 hrs. thereafter or as indicated by Condition Indicator.
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5. Hydraulic Return Filter
Interval - Change after first 50 hours and every 6 months or
300 hours thereafter or whenever Charge Filter is replaced
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