18hp vtwin needs a new carb, maybe...?

[fisk33]

I bought a 18hp big block from CPP about six or seven years ago. It's been running great for the last few years but started having some issues two weeks ago. Sometimes, it would start up and immediately die. I could try several times in a row, and it would start up, but die within 1 or 2 seconds. Sometimes, it would start up and run like a champ. I could drive it around the campground, let it idle for 10 minutes, and drive it some more with no problems at all. And then five minutes later, it wouldn't start again.

I'm no mechanic, but I did change the fuel filters and clean out the carburetor as best I could. And by that, I mean I took off the top and cleaned what I could see. I also took off the float and the little stopper to make sure it's getting fuel. When I turned it over, gas sprayed several inches so I know it's getting fuel. After trying to clean it out myself, it still did the same thing.

I took it to a lawn equipment/small engine place and described what was happening. They called me the next day and said the carb just had too much gunk in it and it needed a new carb. Is this possible? If it runs great part of the time, how could it need a new carb? He said he actually removed it from the engine to get a good look at it, which I didn't do. Is it possible it's so dirty he can't clean it, or is he selling me a new carb I don't actually need? As usual, I feel like i'm getting ripped off. FYI: I reluctantly agreed so i'm getting a new carb and I should get it back tomorrow. I told him I wanted the old one to clean up and keep as a spare, but I really want to look at it and see how bad it is. Well, not that I would know what's very bad or a little bad when it comes to gunk... LOL

I made this video and put it on youtube to show what it's doing: https://www.youtube.com/watch?v=7aGAoc2eAJs

Any opinions are welcome.