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How to Fix a Chain on a Black & Decker Alligator

Updated February 21, 2017

The Black and Decker Alligator is an efficient lopper that can cut small branches and shrubs with ease. The chain is the key component in the cutting process. If the chain isn’t functioning properly, the lopper will not cut the wood, and can even cause the chain to slip off the bar. Fixing the chain on a Black and Decker Alligator is similar to fixing chains on most other chain saws.

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  1. Turn off and unplug the lopper. Spin the chain with your gloved hand to make sure the chain can slide freely over the guide bar.

  2. Loosen the chain cover’s retention nuts with the wrench until they can be removed by hand. The retention nuts are located opposite of the muffler.

  3. Loosen the bar’s tension screw with the screwdriver until the chain hangs slack below the bar.

  4. Unscrew the retention nuts all the way and take off the chain cover and the chain from the bar. Clean the bar and chain by wiping them down with the rag. With the screwdriver, clean out the small guide slots along on the guide bar. Clean the engine housing underneath the chain cover.

  5. Check the sprocket by pulling off the clutch housing. The clutch housing will be the circular metal device that the bar and chain rest on. Use the screwdriver to loosen the clutch screw, then pull off the clutch assembly.

  6. Replace the sprocket if it is chipped or broken. Replace any other damaged or heavily-worn clutch parts. Put the chain and bar back on.

  7. Reassemble the sprocket and clutch assembly in the reverse order you took them off. Re-tighten the clutch bolt to secure the housing in place.

  8. Remove the oil cover, located on the opposite side of the chain cover, using the screwdriver. Add enough fresh oil to fill up the tank. You need to add oil about every ten minutes during cutting to keep the chain spinning along the guide bar, and to keep the engine from overheating.

  9. Tip

    Do not over-tighten the chain to the guide bar. This will cause the tip to heat up and the engine to burn out. Replace chain when the teeth are broken, chipped or missing.


    Always wear the proper personal protective equipment when working with the Black and Decker Alligator.

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Things You'll Need

  • Leather Working Gloves
  • Wrench
  • Screwdriver
  • Rag
  • Oil

About the Author

Eric Blankenburg

Currently based in Minneapolis, Minn., Eric Blankenburg has been a freelance journalist since 2000. His articles have appeared in "Outside Missoula, Outside Bozeman," "Hello Chengdu" and online at GoNomad.com and various other websites. He holds a Bachelor of Arts in creative writing from the University of Montana.

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