Tighten the spray assesory on the kitchen sink. It is diffficult ( impossible) to tighten because of its location beneath the sink. Common tooks are not up to the task, Finger tightening is not adequate.

Turn off the water supply valves beneath the kitchen sink. Turn on the faucet and squeeze the trigger on the sprayer to empty any water left in the supply lines, faucet and sprayer.
Trace the sprayer hose from the end of the sprayer to where it connects to the faucet. Use pliers to loosen the connector holding the sprayer hose to the faucet.
Remove the sprayer hose from the faucet to expose the male threads. Wipe the threads dry with a towel. Wrap the threads with pipe-joint tape. Twist a 3/8-inch threaded brass flair cap onto the male threads. Use the pliers to tighten the cap.
Reach beneath the sink and loosen the mounting nut securing the sprayer support to the sink or countertop. Use a basin wrench if you are unable to reach the mounting nut with your hand.
Slide the mounting nut off the hose attached to the sprayer beneath the sink. Pull the sprayer support and the sprayer from the hole in the sink or countertop.
Insert a sink hole cover into the hole left by the sprayer. Depending on the style of hole cover, it could snap in, or a mounting nut could hold it in place.

Things You Will Need

• Pliers
• Towel
• Pipe-joint tape
• 3/8-inch threaded brass flair cap
• Basin wrench
• Sink hole cover

You will need a basen wrench ( a special wrench to tighten nuts that secure faucet to sink) and open end wrenches. First shut off both hot and cold water valves. Using open end wrench, disconnect hoses from valves. Now, you must loosen both nuts (under the sink towards back wall) Using the basen wrench. After removing nuts, lift faucet up

Assemble the hardest part first, but don't tighten it up. Connect the other parts, but don't tighten. Go back to your hardest piece and tighten. Then tighten the remainder.
Best regards, W/D

from underneath,may be really tricky to get a grip on you might need a basin wrench.

There should be a nut hatched to faucet. If not there look in cabinet.

yes there is, with a pair of slip joints you can tighten from underneath, it is above the supply line, the best thing to do is turn off the water, disconnect the supply line and tighten the nut, then reconnect the supply line and turn back on the water. Good Luck Tim

http://www.needplumbingsupplies.com/Grohe-Kitchen-Sink-Faucets.asp?id=13758

This link has a spec sheet that will give you an view of under neath counter top. There should be a nut that you can tighten it up with.

Remove spray head then faucet tighten connection on the spray hose

pull out the spray part and tighten the nut around the hose or take it loose and replace the washer

I hope this helps.
Step11Turn off the water supply. You'll find a shut-off valve under your kitchen sink. Once the water is turned off, open up the kitchen faucets to allow the water remaining in the pipes to drain way. Step2Catch the drips by placing a bucket under the hot water supply line, located on the left side of your sink. Even a minimum of water can cause a mess and be potentially damaging. Step3Use a wrench to remove the compression nut that secures the hot water supply line. Let the disconnected section fall into the bucket. Use the wrench to loosen and remove the nut at the other end of the line and remove it as well. Step4Repeat Steps 2 and 3 for the cold water supply line. Step5Replace the cold water supply line. Hand-tighten the nuts on both ends, then use the wrench to tighten the nuts completely. Repeat the process with the hot water supply line. Step6Turn on the water supply and test for leaks