I have recently taken my 1999 yamaha YZ400F to the shop. They told me that the 1999-2001 FCR39H carbs had a problem with leaking fuel internally. They claim that the problem is one that can't be fixed. They recommended that I shop for a FCR-MX 39 that is newer than 2002. Has anyone came across this problem and been able to fix it without replacing the carb?