How to Tell If a MiraBot Servo or Servo Gear Is Damaged

If one of your MiraBot servo arms behaves abnormally, or if the device’s movement becomes distorted, the issue may be related to the servo.

However, this does not always mean that the entire servo must be replaced.

A servo contains a motor, position sensor, control board, cables, and a multi-stage gear train. In many cases, abnormal movement or noise is caused by worn or damaged internal gears while the motor and electronic components are still functioning normally.

The checks below can help you identify the likely cause and choose the appropriate repair option.

Before You Start

Stop using the device if you notice:

• abnormal or uncontrolled movement;
• strong vibration;
• clicking or grinding noises;
• unusually high temperature; or
• a servo arm that becomes stuck.

Before manually checking a servo arm, disconnect both the external power supply and the USB cable.

Do not force the servo arm by hand, especially while the device is powered on.

1. Confirm Whether One Servo or All Servos Are Affected

First, observe whether the problem affects:

• one individual servo arm;
• several servo arms; or
• all servos at the same time.

If only one arm behaves abnormally while the others continue working normally, the issue is more likely to be related to that individual servo or its connection.

If all servos stop moving at the same time, the problem is usually not caused by the internal gears of one servo. Refer to the section What If All Servos Stop Moving? below before replacing any parts.

2. Check the Servo While the Device Is Powered Off

With the device completely powered off, gently move the affected servo arm through a small range.

A normal servo will usually have some resistance from its internal gear train, but the movement should feel relatively even.

Compare the affected servo with another servo of the same type where possible.

Possible signs of internal gear wear or damage include:

• clicking or grinding sounds;
• a noticeable skipping sensation;
• uneven resistance during movement;
• excessive free movement or backlash;
• a point where the gear train slips; or
• the output arm moving without properly engaging the internal mechanism.

Do not rotate the arm beyond its normal mechanical range.

3. Check the Servo After Power-On

Reconnect the device and power it on without applying an external load.

The servo arm should normally move to its initial position and maintain that position.

Do not deliberately push or twist a powered servo arm. Use only visual observation and very light contact when necessary.

Possible signs of a servo-related fault include:

• the arm does not return to its normal initial position;
• the arm cannot maintain its position;
• the servo shakes or jitters continuously;
• the motor can be heard running, but the output arm does not move correctly;
• the arm moves intermittently or slips under light load;
• clicking or grinding sounds occur during movement; or
• the servo becomes unusually hot.

These symptoms can have different causes, so the next step is to distinguish likely gear damage from other servo faults.

4. Is the Problem Likely Caused by the Gears?

Like all mechanical components, servo gears gradually wear over time, even under normal use. Heavy loads or unusually intense movement may accelerate this wear and can eventually cause gear damage.

The issue is more likely to involve the internal gears when:

• the servo motor can still be heard operating;
• the output shaft moves partially but slips or skips;
• clicking or grinding sounds come from inside the servo;
• the output arm has excessive free movement;
• movement stops under load but resumes after the load is removed; or
• damaged or missing gear teeth are visible after inspection.

When gear damage has been confirmed, it may not be necessary to replace the complete servo.

The internal gear train and output shaft bearing can be replaced using the MiraBot Servo Replacement Gear Kit.

5. When the Complete Servo May Need to Be Replaced

Replacing the gear set will not resolve faults involving:

• the servo motor;
• position sensor;
• internal control board;
• power or signal cable;
• connector;
• damaged servo housing; or
• other electronic components.

A complete servo replacement may be more appropriate when:

• the servo produces no sound or movement despite receiving the correct power and signal;
• there is no holding torque after power-on;
• the servo becomes unusually hot without a mechanical blockage;
• the movement remains unstable after the gears have been inspected or replaced;
• the cable or connector is damaged; or
• the motor, sensor, or control board has been confirmed faulty.

Use only a compatible replacement servo.

MiraBot S6 and MiraBot Lite use the MBS2035 servo in 180° and 270° versions. Confirm the required angle version and installation position before replacement.

6. What If All Servos Stop Moving?

If all servos stop moving at the same time, do not assume that multiple servos have failed simultaneously.

Check the following first:

• external power adapter and power cable;
• power connections inside the device;
• Controller Kit startup status;
• loose or disconnected wiring;
• firmware status; and
• USB or communication connection.

Please refer to:

What Should I Do If My MiraBot Does Not Move After Powering On?

7. Tips to Help Extend Servo and Gear Life

Servo gears are moving mechanical components and will gradually wear with use. The following practices can help reduce unnecessary stress:

• Do not operate the device when its movement is physically obstructed.
• Avoid applying excessive external force to the servo arms.
• Keep the attached load within the recommended range.
• Make sure all accessories and mounting components are installed correctly.
• Avoid prolonged high-speed or unusually aggressive movement.
• Stop the device if clicking, grinding, strong vibration, or abnormal resistance appears.
• Do not force the servo arms while the device is powered on.
• Inspect abnormal movement promptly before continued use causes additional damage.

Choosing the Appropriate Repair Option

Use the following guide as a general reference:

Repairing Instead of Replacing the Complete Servo

When only the internal gears are damaged, replacing the complete servo may result in unnecessary cost and waste.

The MiraBot Servo Replacement Gear Kit provides a lower-cost repair option for the MBS2035 servos used in MiraBot S6 and MiraBot Lite. By replacing only the worn mechanical components, users can restore normal torque transmission and extend the usable life of the servo.

MiraBot Servo Replacement Gear Kit

How to Replace the Servo Gears in Your MiraBot

Need More Help?

When the symptoms do not clearly indicate whether the issue is caused by the gears or another servo component, avoid continuing to operate the affected servo until the cause has been identified.

For unresolved hardware issues, a Support Request can be submitted with the device model, affected servo position, and a short video showing the abnormal movement.