10
JAT-401,402 Die Grinders
Troubleshooting JAT-401/402 Die Grinders
Any disassembly of the tool should be done by qualified service personnel. For problems not addressed
below, contact JET technical service at 800-274-6846.
Problem
Possible cause
Remedy
Tool will not start.
Air valve closed or obstructed.
Open valve; clear any obstructions.
Dirt or gum deposits on
components.
Flush tool with gum solvent.
If problem persists, disassemble,
clean and lubricate internal parts.
Rotor vanes or other components
are worn.
Replace worn components.
(Replace vanes as an entire set.)
Throttle lever malfunction.
Clean throttle lever mechanism to
ensure free movement. Replace
mechanism if needed.
Bearing(s) worn.
Disassemble and inspect bearing.
Grease or replace as needed.
Starts immediately as soon
as air is connected without
lever being pressed.
Throttle valve malfunction.
Inspect and repair throttle valve.
Excessive or abnormal
vibration.
Improper lubrication.
Lubricate properly according to
instructions in this manual.
Bearings worn.
Disassemble and inspect bearing.
Grease or replace as needed.
Loss of power; erratic
action.
Low air pressure.
Verify compressor has proper CFM
rating for tool.
Check compressor regulator
setting; set air pressure to 90 psi.
Check for loose connections at air
inlet, o-rings, etc.
Moisture or obstruction in air
hose.
Air supply must be clean and dry.
Clean out air hose(s) and remove
any kinks or bends.
Improper size of air transmission
lines, hoses, fittings, or
couplings.
Use appropriate-sized air
lines/hoses.
Verify proper fittings/couplings.
Dirt or gum deposits on
components.
Flush tool with gum solvent.
Check and clean air filter on
compressor.
Clean external areas of tool. If
problem persists, disassemble,
clean and lubricate internal parts.
Rotor vanes are worn.
Replace vanes (entire set).
Severe air leakage.
(Note: Minimal escape of
air is often normal for air
tools.)
Air valve obstructed or damaged.
Clean or replace.
Housing loose or damaged.
Tighten or replace as needed.
Excessive heat develops
in tool.
Improper lubrication.
Lubricate properly according to
instructions in this manual.
