My wife noticed that the kitchen faucet (Delta single handle with sprayer) is not securely attached to the sink. I looked underneath, and see that the nut and large metal washer are on the side away from the sprayer, but the sprayer side nut is not installed. That side takes a plastic nut that goes over the pipe/sleeve that the sprayer hose goes though. Luckily, I had a spare one in my plumbing stuff drawer. This faucet was put in around 1988, so after removing the sprayer hose, I still couldn't get the nut onto the pipe thread because it was so oxidized, or maybe the threads are clogged with calcium that dripped down over the 30 years of use. I tried cleaning the threads with a small screwdriver and a plastic Scotch-Brite pad. No luck. Is there something else I can do to secure the faucet? I'm picturing a split nut that slides over the bad threads and snaps onto the pipe where the threads are still ungunked up. Or maybe there's some old plumber's trick I never heard of. Thanks in advance.