the blade on my rear handle saw wobbles side to side when it's running, not cutting straight anymore.

Diagnosis

The side-to-side wobble (lateral runout) on the Makita XSR01Z is typically caused by a failure in the blade seating surface or a misalignment of the arbor assembly. Because this is a high-torque 36V XGT tool, any slight debris—such as a single sawdust pellet or a metal chip—trapped between the inner arbor flange and the blade will push the blade off-center. This creates a centrifugal imbalance that manifests as a visible wobble and results in skewed, non-perpendicular cuts. If the flanges are clean, the issue is likely a deformed outer flange or a bent arbor shaft. This often happens if the blade bolt was over-tightened using an impact driver rather than the provided wrench, or if the saw suffered a "kickback" event that put sudden lateral pressure on the spindle. To confirm, run the saw at low speed and observe the blade from the side; if the blade "hula-hoops" while the shaft remains steady, the blade is warped. If the entire assembly shifts, the arbor shaft is bent.

How to Fix It

Follow these steps to reset the blade alignment and ensure a true cut:

1. Remove all 36V XGT batteries from the tool to prevent accidental startup.
2. Using the provided blade wrench, loosen the arbor bolt. Remove the outer flange and the circular saw blade.
3. Remove the inner arbor flange (the large washer resting against the motor housing).
4. Use a lint-free cloth and a degreaser or compressed air to thoroughly clean the arbor shaft and both flanges. Even a microscopic piece of grit can cause a 1-2 degree tilt.
5. Inspect the inner flange for any gouges or "burrs" in the metal. If you see scoring, use a fine-grit emery cloth to smooth the surface.
6. Reinstall the inner flange, ensuring it seats perfectly flush against the motor housing.
7. Slide the blade onto the arbor. Ensure the teeth are facing the correct direction and that the blade is centered on the flange.
8. Place the outer flange on top. Hand-tighten the arbor bolt first to ensure the threads are engaged correctly.
9. Using the blade wrench, tighten the bolt firmly. Do not use an impact wrench, as over-torquing can warp the flange or strip the bolt threads.
10. Run the tool at a low speed to verify the wobble has ceased before attempting a test cut.

If That Didn't Work

• Replace the Blade: If the wobble persists with clean flanges, the blade itself is likely warped. Even high-end carbide blades can develop a slight bend if dropped or subjected to extreme heat. Swap in a brand new, certified 36V-compatible blade to see if the runout disappears.
• Inspect the Outer Flange: Check the outer flange for flatness. If the flange is slightly concave or convex due to over-tightening, it will apply uneven pressure to the blade. Replace the flange (Part # available through Makita XGT spares) if it is not perfectly flat.
• Check for Bearing Failure: If you hear a grinding noise accompanying the wobble, the internal motor bearings may have failed or shifted. This requires a teardown of the gear housing to inspect the arbor bearing race for pitting or play.
• Verify the Base Plate Alignment: Ensure the shoe (base plate) isn't bent. If the shoe is skewed, the saw may appear to be cutting crooked even if the blade is spinning true. Place a machinist's square against the blade and the shoe to verify a perfect 90-degree angle.

Heads Up

• Never use an impact driver to tighten the arbor bolt; the XSR01Z requires precise torque to keep the blade stable without distorting the flanges.
• Always clear the arbor of sawdust before every blade change; "debris-induced runout" is the number one cause of crooked cuts in rear-handle saws.
• Check the blade bolt every 20-30 minutes of heavy use, as the high torque of the 36V system can occasionally vibrate the bolt loose.
• Only use blades rated for the high RPMs of the XGT line to avoid centrifugal stretching or catastrophic blade failure.