Steve,
I am no expert, but I suspect that’s a stuck float needle. Running some fresh fuel through the carbs can help, or give the carb a good tap with a rubber mallet, that works sometimes as well.Otherwise you will have to strip and clean.
Whenever I put my bike away, I always switch off the fuel tap about a mile from home , then when I get home I leave the bike on until the carbs run dry. I was told to do this a long time ago when I first started riding bikes ( like 35 years ago ) and I have never had an issue with gummed up carbs/stuck valves .
Obviously that doesn’t solve your immediate issue but may be the thing to do in the future.
Regards,
Nat