Quick Answer:
If the stopper works some days and fails on others, the most common causes are a slightly loose pivot nut or a slipping linkage clip. Start by tightening the pivot nut just a little and checking the clip that connects the pivot rod to the stopper. Follow the steps below to confirm and fix the problem safely.
Why This Happens
Intermittent operation usually means the mechanical linkage that lifts and lowers the stopper is not staying in the correct position. Causes include:
- Pivot nut that is a bit loose, allowing the rod to shift under load.
- Retaining clips that have worn, bent, or are not fully seated and slip out of place.
- Debris, corrosion, or limescale that changes how the parts move depending on moisture and position.
If the problem appeared after cleaning or a maintenance job, check for trapped debris or a jammed assembly — this can be related to Pop-up jammed after cleaning.
Step-by-Step What to Do
1. Prepare the area
- Place a small bucket under the P-trap to catch any water or parts that fall.
- Clear the cabinet so you can reach up to the drain assembly comfortably.
- Wear gloves and have a towel handy for grip and cleanup.
2. Test the linkage
- Operate the lift rod while watching the horizontal pivot rod under the sink. Note whether the rod moves smoothly and whether the stopper moves every time.
- If the stopper sometimes lags or doesn’t follow the rod, the connection where the pivot rod meets the stopper is suspect.
3. Tighten the pivot nut slightly
- Find the nut that clamps the pivot rod to the tailpiece (pivot nut). Use your fingers or an adjustable wrench.
- Turn the nut a small amount — usually a quarter turn is enough. The goal is to remove play without stopping the rod from moving.
- Test the stopper several times. If it still slips, tighten another small amount and test again. Avoid overtightening.
4. Inspect and secure the clip
- Locate the clip that attaches the pivot rod to the stopper’s strap or post. It is often a spring clip or C-clip.
- Ensure the clip is fully seated in its groove and not bent or deformed. If it looks loose, push it into place until it snaps or seats securely.
- If the clip is damaged or stretched, replace it. A faulty clip can let the linkage slip and suddenly disconnect.
5. Clean and test the stopper
- Remove the stopper (if your design allows) and clean any gunk on the pivot rod, stopper post, and inside the tailpiece.
- Reassemble and operate the rod through its full motion several times to confirm consistent movement.
- If the stopper still does not move reliably, check for bent rods or damaged internal parts that may need replacement.
6. Additional troubleshooting
- If the stopper raises but won’t fully open, consult guidance on Pop-up drain won’t open.
- If the pivot nut or rod is corroded or the nut won’t tighten, you may need to replace the pivot rod assembly.
What Not to Do
- Do not ignore intermittent failures; loose clips can fully disconnect suddenly.
- Do not overtighten the pivot nut — overtightening can bind the mechanism or strip threads.
- Do not glue or force parts together. Permanent fixes like glue can prevent future maintenance and cause more damage.
When to Call a Professional
Contact a plumber if:
- The pivot rod or nut is corroded, bent, or broken and replacement is difficult to reach.
- Tightening and replacing clips does not stop intermittent failures or the drain leaks after repairs.
- Multiple parts are worn or the stop-and-go behavior continues despite basic repairs.
Safety Notes
- Work with the area dry when possible; water makes clips and small parts slippery.
- Use a bucket under the P-trap to avoid spills and catching dropped parts.
- Wear gloves to avoid cuts from sharp metal edges under the sink.
- If you use chemical cleaners to remove buildup, follow the product instructions and ventilate the area.
Common Homeowner Questions
- Why does it only fail sometimes? Small play in the linkage or a partially seated clip can let the connection slip under certain positions or loads.
- Can I fix it without removing the sink? Yes — most fixes (tightening the pivot nut, reseating or replacing the clip, cleaning) are done from under the sink.
- How much should I tighten the pivot nut? Tighten a little at a time — a quarter-turn increments — until play is gone but movement is still smooth.