I have a Kohler kitchen faucet, installed about 2.5 years ago, with a very annoying problem.I lost the original paperwork so there is no record as to the model, can only say its a single handle, with a spray that pulls out of the faucet. The problem is it shuts itself off such that you can only run it a high volume. The handle drops down and won't stay at a low flow rate. I had my plumber look at it and he did not know the fix, suggesting I try the internet. This is the only problem the faucet has. Any advice will be welcome.