I’ve also found debris stuck in the fuel lines after replacing the fuel filter and removing the cap to check. Once it was dead wasps… Blew out the fuel lines and has been running great for several years.
Pull the spark plug. If it’s dry, then it’s likely fuel starved. Either a clogged fuel cap vent or a misadjusted fuel float/needle valve. If it’s wet, then the fuel bowl is probably adjusted too low.
Beyond that, could be a bad coil or ground.
JB Weld also makes a two-part epoxy for plastic, including thermoplastics. It worked great on my Ferris hydraulic oil tank. Sets up in 15 minutes and cures in about 30 minutes. Strong as hell, too.
Had the same issue on my new Ferris Procut S 61. Always garaged and maintained well. Started leaking after 150 hours or so. Really poor design for a pricey mower! Thought about threading up a replacement bulkhead fitting but couldn’t come up with a good setup. I went with Slomo’s suggestion...