How Do I Repair a Hermle 340-020 Clock Movement?

Hermle 340-020 Clock Repair

Whether you inherited a clock with this movement or your beloved timepiece has started losing time or skipping chimes, you might be wondering: Can I repair a 340-020 clock movement—or should I replace it?

In this comprehensive Q&A, we’ll walk you through the process of diagnosing, repairing, or replacing a Hermle 340-020. We’ll also help you decide which route makes the most sense for your clock’s condition and your budget.

1. What is the Hermle 340-020 movement?

The Hermle 340-020 is a spring-driven, 8-day mechanical movement that powers many modern clocks with a Westminster chime. It features front-mount chime hammers, three winding arbors, and often appears in clocks manufactured after the 1970s. Hermle built this model for reliability and consistency, which makes it a solid candidate for repair—if the damage isn’t too extensive.

2. What are the most common problems with a 340-020 movement?

You may notice:

• The clock runs erratically or stops altogether
• The chimes are off-time or don’t strike at all
• It won’t keep accurate time, even after winding
• One or more winding arbors are stiff or locked
• The pendulum stops swinging prematurely

These problems typically stem from old oil, worn bushings, bent levers, or weakened springs. Over time, any mechanical movement will wear out—especially if it hasn’t been cleaned or serviced every 7–10 years.

3. Can I repair a 340-020 clock movement myself?

Yes—but only if you’re comfortable with mechanical systems and willing to work carefully. The 340-020 movement contains dozens of small parts, and repairing it requires precision and patience.

You’ll need:

• A mainspring let-down tool
• Clock bushing tools (or pre-bushed plates)
• Clock oil and cleaner
• Possibly a bushing press or staking tool

Before starting, disassemble the movement completely. Photograph every angle beforehand and label gear positions to avoid confusion during reassembly. Use an ultrasonic cleaner or Clockworks’ recommended [clock cleaning solution]() to remove old oil and grime. Inspect each pivot hole and gear tooth for signs of wear or damage.

If you find excessive play in the pivot holes or grooves worn into the pivots, you’ll need to bush the plates and polish the pivots. Failing to fix this wear will only cause the clock to stop again in short order.

4. How do I know if the movement is beyond repair?

Inspect the gear train and the chime locking mechanism. If you find:

• More than 4–5 bushings that need replacing
• Severely worn gear teeth
• Bent or broken levers
• Excessive rust or plate warping

Then the movement likely isn’t worth the time and cost of a full restoration. While a skilled repairer can technically fix most issues, the cost in hours and parts often outweighs the benefit—especially when high-quality Hermle 340-020 replacements are widely available.

5. Should I replace the 340-020 instead of repairing it?

In most cases, yes. Clockworks offers brand new Hermle 340-020 movements, manufactured in Germany and designed to drop in with no modification required. If your clock case and hands are in good condition, replacing the movement can restore full functionality without the hassle of repair.

Installing a new unit takes less than an hour for most DIYers. The steps include:

1. Remove the hands and dial
2. Disconnect the chime rods
3. Unscrew the movement from the case
4. Install the new 340-020
5. Reattach the chimes, dial, and hands
6. Level the clock and set the beat

We include detailed installation instructions with every purchase.

6. What tools do I need to install a replacement 340-020 movement?

You won’t need specialized horology tools for a basic swap. Grab:

• A set of screwdrivers 
• A set of Pliers
• Patience and steady hands

If your clock uses a pendulum, don’t forget to hang it correctly and adjust the beat by ear. If it ticks evenly—like a metronome—it’s properly set. If it ticks unevenly, tilt the clock left or right until the rhythm becomes consistent.

7. How long will a new 340-020 movement last?

With regular maintenance, a brand-new 340-020 should last 15 to 20 years. You’ll want to oil the movement every 2–3 years and fully clean it around year 10.

Avoid exposing the clock to extreme humidity, direct sunlight, or freezing temperatures. These conditions will accelerate wear and warp the brass parts over time.

8. How can I tell I’m buying a genuine Hermle movement?

When shopping for a 340-020, check for:

• “Hermle” and “Made in Germany” stamped on the backplate
• Correct movement number (340-020) near the winding arbors
• Matching pendulum length (if applicable)
• Trusted supplier—like Clockworks, which sources directly from Hermle

Some knockoffs exist online, and they often fail within a year. Stick with authorized dealers who offer support, warranties, and technical guidance.

Summary: Repair vs. Replace?

Need Help With a Hermle 340-020?

Clockworks, Inc. stocks genuine replacement Hermle 340-020 movements and all the parts, tools, and guides you need. Whether you’re ready to repair your own movement or want to swap it out with a fresh one, we’re here to support your project.

Visit Clockworks.com or email clockworks@clockworks.com and we’ll help you keep your clock ticking.

Updated on: 06/10/2025