My lever style kitchen sink faucet leaks where it

tighten it

Needs to be tightened from under the sink, may need a right angle faucet wrench, they are about $10, or you can try and snug it up by hand, hope this helps?

There is a nut up under the counter its hard to see but tighten that . Most faucets come with a special tool fo hat but can be done with wrench

Probably a loose fixture nut under the counter behind the sink.
Yeah ya gotta pull out everything and crawl up into the cabinet on your back and see if the nut (right up at the granite, above the hot and cold inlet pipes) is loose. If it is THEN you'll need to tighten it. Wrench, slip-joint pliers or a basin wrench. (probably basin wrench which is a specialized tool made for reaching up into tight places)

you tighten it from under the sink

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.

Turn off the water supplies . Disassemble the unit until you can lift the spout up and off of the base unit.Replace "O" rings and lube well with a good heat/water resistant grease. (PLUMBERS GREASE) sold at hardware stores. Carefully reinstall back the opposite the way it was disassembled. Lube all moving parts where contact is made during reassembly.Its easy it should not be a problem for you to do with simple tools (Allen wrench) and confidence.Check to make sure the "O" rings are in good shape and replace if necessary

there are mounting plates underneath the counter which fasten the faucet to the counter.This unit will need a small allen wrench if memory serves me correctly...keep in mind that all moen faucets are lifetime guranteed and alot of folks do not take advantage of this amazing warranty which makes these the most desirable faucet on the market.however the need to tighten this faucet prob isnt a warranty replacement procedure but can be determined once mounting items and faucet is inspected...good luck