Question 1

wheel wobbles side to side even with a new disc and tight nut, seems like the shaft is bent.

Accepted Answer

DIAGNOSIS This is either a bent output shaft or a damaged spindle thread. Forcing a stuck nut or dropping the tool on the wheel can cause this. FIX Confirm by removing the disc and nut. Spin the shaft by hand while watching the very end of the threads. If you see a wobble, the shaft is bent. Replacing the output shaft requires a full gearbox teardown and press work to remove the old shaft and bearing. IF THAT DIDN'T WORK The wobble might be from a worn spindle bearing, allowing lateral play. Check for up/down play in the shaft. If there's movement, the output shaft bearing is shot. HEADS UP A wobbly wheel is dangerous. It increases the chance of disc shatter and causes uneven wear, overloading the tool. Stop using it immediately.

Question 2

the safety paddle switch is super stiff and sometimes sticks in the on position, scary.

Accepted Answer

DIAGNOSIS Grinding dust and grit have infiltrated the switch mechanism. The dust mixes with grease and forms an abrasive paste that jams the sliding parts. FIX The switch must be cleaned or replaced. Housing disassembly is required. Once open, you can access the paddle switch. Blow it out thoroughly with contact cleaner, not WD-40. Work the switch repeatedly to free it. If it's physically damaged, replace the entire switch assembly. IF THAT DIDN'T WORK The internal return spring for the switch may have broken or dislodged. This requires opening the switch housing to inspect, which often means replacement is easier. HEADS UP A sticking switch is a severe safety hazard. Do not use the tool until this is fixed. Consider taping the switch in the off position while working on it to prevent accidental startup.

Question 3

there's a fine black powder blowing out of the vents near the motor, is my grinder burning up?

Accepted Answer

DIAGNOSIS That's carbon dust. It's normal wear material from the carbon brushes. Excessive dust means the brushes are wearing out faster than usual. FIX Inspect and likely replace the carbon brushes. Remove the two brush caps on opposite sides of the motor housing. Use a small screwdriver to pull out the spring and brush. If the carbon piece is less than 1/4 inch long, replace both brushes (part 903371-1). IF THAT DIDN'T WORK If new brushes still produce a cloud of dust, the commutator on the armature is rough or dirty. This files down the brushes rapidly. The armature may need to be replaced or professionally turned. HEADS UP Keep that dust away from your face. It's conductive and can cause shorts in other electronics. Regularly clean out the motor vents with compressed air to prevent internal buildup.

Question 4

my grinder just blinks the battery light red a few times and won't run at all, battery is charged.

Accepted Answer

DIAGNOSIS The tool's onboard computer is detecting a fault. This is usually an overload/overheat lockout or a communication error with the battery. FIX First, perform a hard reset. Remove the battery. Hold the trigger down for 30 seconds. Reinstall the battery. If it works, the thermal protector just needed to reset. If it still blinks, try a different, known-good LXT battery. This isolates if it's the tool or the battery. IF THAT DIDN'T WORK The problem is in the tool's control board. Moisture or conductive dust can cause a short, triggering the fault light. The board would need replacement. HEADS UP Do not try to bypass this protection. The red blink is preventing a potential fire or motor burnout from a short circuit. It's a critical safety feature.

Question 5

tool gets crazy hot right behind the guard after like 30 seconds of use, way hotter than my old one.

Accepted Answer

DIAGNOSIS This is a sign of excessive friction in the gearbox. Likely causes are old, dried-out grease or a misaligned gear causing binding. FIX The gear case needs regreasing. Disassemble the gear head as described for bearing replacement. Clean out all old, blackened grease with a solvent. Apply a fresh, high-quality moly grease specifically for angle grinder gears. Do not overpack it. IF THAT DIDN'T WORK The motor armature might be rubbing on the field coils due to a bent shaft or failed motor bearing. This creates massive heat that transfers forward. This requires motor replacement. HEADS UP That heat is cooking your seals and bearings. Continuing to run it hot will lead to a complete gearbox seizure. Let it cool down fully before investigating.

Question 6

the spindle lock on my xag04z won't engage, button feels mushy and the shaft just spins freely.

Accepted Answer

DIAGNOSIS The spindle lock pawl is either broken, jammed with debris, or the return spring has come off. It's a common failure point. FIX Remove the wheel guard and spindle nut. Use a small pick to pry out the rubber button cover. You'll see a small screw. Remove it and the metal button plate. Inside, clean out any metal dust. Check the small steel pawl and its pivot pin. Replace the entire lock assembly (part 463642-1) if the pawl is cracked. IF THAT DIDN'T WORK The problem might be deeper. The shaft groove that the pawl engages into could be worn round. This requires replacing the output shaft, a major teardown. HEADS UP Never force the lock button. If it's jammed, you'll snap the plastic housing. Always ensure the grinder is unplugged and the wheel has completely stopped before attempting to lock the spindle.

Question 7

makita grinder makes a loud grinding noise from the gear head, not the disc, sounds like bad bearings.

Accepted Answer

DIAGNOSIS You have a failing pinion bearing or output shaft bearing. Grinding dust gets past the seals and destroys the bearing balls and races. FIX The gear head must be disassembled. Remove the wheel guard and spindle lock nut. Remove the four long bolts holding the gear head to the motor housing. Press out the old bearings. Install new sealed bearings (part 6900 for the pinion shaft, part 6001 for the output shaft). Pack the gear case with fresh grease. IF THAT DIDN'T WORK The noise could be from worn helical gears. Inspect the teeth for chipping or excessive wear. Replace the gear set if damaged. HEADS UP Do not run it with failing bearings. The heat can warp the gear case, turning a bearing job into a full housing replacement.

Question 8

my makita angle grinder just stopped spinning mid-cut, trigger feels normal but nothing happens.

Accepted Answer

DIAGNOSIS This is almost always a failed trigger switch or a loose internal connection. The switch contacts wear out from dust and repeated use. FIX You need to replace the switch assembly. Unplug the battery. Remove the four screws from the rear housing. Carefully separate the halves. Note the wire routing. Unplug the old switch from the motor terminals. Install the new switch (part 192059-5). Reassemble in reverse order. IF THAT DIDN'T WORK Check the carbon brushes. If they're worn down to the nub or stuck in their holders, the motor won't get power. Replace them as a pair. HEADS UP When reassembling, make sure the wires are clear of the gear housing. A pinched wire will cause a short and can damage the electronics.

Makita XAG04Z 18V LXT Angle Grinder

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