I installed my Toto Guinivere about 18 months ago and absolutely love everything about it! I have had no problems until this last week when I noticed there was a delay after flushing of 3-4 seconds before the tank began to refill. I don't know anything about fill valves but this one acts like the incoming water is hung up somewhere before it comes out of the hose and begins to refill the tank. It also sprays water from the side of the valve. I don't know if the valve sprayed water before but I do know the refill action was instantaneous prior to now. We are in a very rural area and I don't think our water pressure is too high and neither does it seem logical that the valve on this great [and spendy] toilet needs to be replaced after only 18 months of use by 2 adults. Any ideas if this is fixable or might just be gunk somewhere? How would I determine that? And if I do have to replace this valve, which one should I purchase? Thanks for any help.