JLG 1250AJP Operator Manual - Manual (Page 111)

SECTION 6 - GENERAL SPECIFICATIONS & OPERATOR MAINTENANCE
3121170 – JLG Lift – 6-21
A - Red = Filter Restricted; Filter Bypassed
B - Green = Filter Good; Not Restricted
Figure 6-7. Hydraulic Return Filter Condition Indicator - Prior to S/N 139396