We have a Delta kitchen faucet with separate sprayer that was making a thump sound when the water was turned on. The problem worsened to the point the water from the faucet would randomly shut off, so we called a plumber, who said the diverter was shot and we needed a new faucet. OK, made sense, so we agreed and a new Delta was installed. Within a week, the problem returned. The plumber came back out and installed another new Delta. This time, with in a hour, the problem returned. Turn on water, thumps, sprayer starts dripping water.

Water pressure reads 80 psi, and plumber says that's fine and he thinks we need a water hammer arrestor. This is starting to get expensive, so I'm just wondering... does this sound like a likely fix? I don't want to keep throwing money away buying parts that aren't solving the issue, and am considering just giving up on having a sprayer, or maybe calling another plumber out for a second opinion. Any thoughts or suggestions appreciated. Thanks!