I have a 40 horse 4 cylinder oil injected mercury engine. model # 1-040411td i want to clean out and rebuild the carbs. the carbs are wma walbro carbs. the ones on the engine dont match the parts drawings i'm finding exactly. they say it has wma-4's but can supersede to a 10, or a 13. mine are stamped wma-2. on the side. there is no listing anywhere for a wma-2. but, on top of the carbs there is a 13 stamped also. so i'm assuming theses are wma-13's. one of the reasons i want to rebuild them is a minor leak at the bottom of the top carb. it seems to be coming out of the throttle shaft bore and running down the link to the top of the bottom carb. at first i thought it was an oil leak from an injection line or something. because it looked like oil rather than mixed fuel. but, i cleaned and dried it off really well with brake cleaner, ran it and watched for it. and comfirmed the location. what seals the throttle shafe in this area? is there a bushing, a seal, or are they simply drilled through the casting? if so can it be restaked for a tighter fit? has anyone else experienced this problem?