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a). Pinched hydraulic lines.
b). Oil viscosity is too heavy.
3. Lift raises, then slowly lowers without power:
a). Leaking hydraulic lines or fittings (check for
telltale oil spots).
b). Check valve in pump -- may not be seating.
Requires new pump.
4. Lift will not lower when energized:
a). Down solenoid faulty. Check voltage -- may be
low or wrong voltage for coil. Check continu-
ity of coil (burned out).
b). Pinched hydraulic lines.
c). Oil viscosity is too heavy.
S E C T I O N 7
SERVICE
A. REPLACING CYLINDER SEALS:
1. Lower the lift to its lowest position. Then lift
the top to its over center position and secure.
2. Disconnect the negative battery terminal.
3. Disconnect the hydraulic hose from the cylin-
der and cap the line to prevent hydraulic fluid
loss.
4. Loosen the set screws holding the cylinder
pin.
5. Remove the cylinder pin.
6. Lift the cylinder out of the lift.
CAUTION!
Hold the cylinder securely while removing the
pin to prevent it from falling to the floor.
7. Clamp cylinder securely at the base end.
8. Completely collapse cylinder piston.
9. Push gland into the cylinder 1/8''- 3/16''.
10.
Remove retaining ring.
11. Remove piston rod, piston and gland from cylin-
der.
12. Remove rod nut, piston and gland.
PRESTO OWNER'S MANUAL
13. Remove and replace seals and wipers.
14. Assemble piston and gland to piston rod.
15. Assemble rod nut to piston rod and torque
to 100 ft./lb.
16. Lubricate piston and seals and install cylinder.
17. Insert retainer ring.
18. Install cylinder and hydraulic lines.
19. Fill reservoir.
20. a). For the lifts serviced in lowered position, lower
tabletop completely.
21. Cycle lift 2-3 times adding oil if necessary.
22. Recheck reservoir oil level.
Page 8
DBP SERIES SCISSOR LIFTS
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