After further review, it's looking like the fuel pump isn't producing enough pressure to push the fuel up the line and into the carb, especially when the needle sticks in the carb. This would likely be due to a worn camshaft lifter for the fuel pump. Has anyone either experienced this or heard of a lifter wearing out like that? If that's the case, I'm looking at either replacing the camshaft or installing a small electric fuel pump. Any thoughts or suggestions are appreciated! Thanks!