A kitchen basket strainer connects the sink to the drain pipe and is the piece the drain stopper fits down into. You may need a new basket strainer if you experience leaks and retightening the locknuts and slip nuts does not seem to stop the problem. When purchasing a new basket strainer, buy a better quality basket strainer and avoid thin metal or plastic strainers that won't last as long. Set aside at least two hours to complete the project.
Remove the tailpiece connected to the basket strainer from under the sink by unscrewing the tailpiece's top and bottom slip nuts with a spud wrench or groove-joint pliers. Inspect the tailpiece washers. If they are worn, buy replacements.
Detach the basket strainer's locknut by turning it counterclockwise with a spud wrench or groove-joint pliers. Remove and inspect the rubber and fibreglass washers. Purchase replacement washers if they are worn.
Remove the basket strainer from above the sink and set it aside. Strip away the putty from around the drain hole with a plastic putty knife. Wipe away any residue with a clean rag.
Roll plumber's putty into a snake and apply it to the underside rim of the new basket strainer. Set the new basket strainer into the drain hole and press into place.
Reassemble the basket strainer. Have someone hold the basket strainer in place from above the sink by inserting the handles of a set of pliers into the drain hole of the basket strainer. Insert a screwdriver between the pliers' handles to stop movement. Replace the rubber and fibreglass washers from under the sink and retighten the locknut by turning it clockwise with a spud wrench or groove-joint pliers.
Scrape off any excess plumber's putty from above the sink with a plastic putty knife. Wipe residue away with a clean rag.
Hold the tailpiece back in place and retighten the top and bottom slip nuts with a spud wrench or groove-joint pliers. Set the stopper into the basket strainer and fill the sink with water to check for leaks. Pull the stopper up to allow the water to drain and look for leaks.
Take old washers to the store with you to purchase replacements. Clean out the area under the sink to give you room to work. Set a bucket under the sink to catch water.