my dewalt impact driver won't change speeds, it's stuck on mode 1 no matter how many times i click the collar.

Diagnosis

The DeWalt DCF887B utilizes a mechanical detent system involving a spring-loaded ball bearing or plastic tab that locks into specific notches on the internal gear selector shaft. When the tool is "stuck" in Mode 1, it typically means the external plastic collar has decoupled from the internal metal selector pin, or the detent spring has collapsed/jammed due to accumulated construction debris, metallic shavings, and dried lubricant. Because this tool is frequently used in high-dust environments, fine particulates migrate under the rubber grip and enter the selector housing. This creates a "sludge" that prevents the collar from fully engaging the gear shift. You can confirm this by feeling the "click" as you rotate the ring; if the rotation feels smooth or "mushy" without a sharp tactile snap, the collar is spinning freely without moving the internal selector, leaving the tool locked in the lowest speed setting.

How to Fix It

To resolve a jammed or decoupled selector ring, you must perform a deep chemical flush and a mechanical reset of the collar alignment.

1. Remove the 20V Max battery pack to ensure the trigger cannot be accidentally depressed during the process.
2. Use a precision flat-head screwdriver or a dental pick to gently pry the edge of the rubberized grip boot away from the plastic housing specifically around the speed selector collar. Do not rip the rubber; just create a 2mm gap.
3. Apply a generous amount of high-pressure electrical contact cleaner (such as CRC QD Contact Cleaner) or 99% Isopropyl Alcohol directly into the gap between the rotating collar and the main tool body. Focus the spray on the area where the collar meets the motor housing.
4. While the solvent is still wet, rotate the collar rapidly between Mode 1, 2, and 3. Do this at least 30-50 times. You are attempting to dissolve the grit and push it out of the detent notches.
5. If the collar still feels loose, apply a firm axial push—press the collar inward toward the motor while simultaneously twisting it to Mode 3. This often reseats a collar that has slid off its internal track.
6. Once you feel the tactile "click" return, spray a tiny amount of dry PTFE lubricant into the gap to prevent future debris adhesion.
7. Allow the solvent to evaporate for 5 minutes before re-inserting the battery and testing the RPM change.

If That Didn't Work

• Internal Detent Spring Replacement: If the collar spins but there is no resistance, the internal spring has likely snapped. You will need to remove the housing screws (T10 Torx) and carefully split the clamshell. Locate the selector shaft and replace the detent spring and ball bearing. Ensure the spring is seated firmly in its pocket before closing the case.
• Collar Tab Reconstruction: Inspect the inside of the plastic collar. If the internal plastic ribs that grip the selector shaft have worn down or stripped, the collar will spin without engaging. You can temporarily fix this by applying a thin strip of heavy-duty grip tape or a small amount of high-strength epoxy to the internal diameter of the collar to create a tighter fit on the shaft.
• Housing Obstruction Clearout: In some cases, a small piece of debris (like a metal chip from a screw) gets lodged directly in the gear track. With the housing open, use compressed air to blow out the selector assembly from the inside out, ensuring no foreign objects are blocking the travel of the selector pin.
• Full Selector Assembly Swap: If the internal gear selector shaft is bent or stripped, the entire selector assembly must be replaced. This involves removing the motor and gearbox to access the shifting mechanism.

Heads Up

• Avoid using WD-40 or heavy oils for cleaning the selector; these attract more sawdust and metallic grit, which will cause the mechanism to jam again within weeks.
• Never force the collar with pliers if it is stuck; the plastic housing on the DCF887B is prone to cracking if excessive torque is applied to the speed ring.
• Periodically blow out the selector area with compressed air every 20-30 hours of heavy use to prevent debris buildup.
• Always ensure the battery is removed before prying at the rubber boot to avoid shorting any internal components with metal tools.