Toro Workman hard starting

Hi I have a Toro Workman 2100 with 16 hp B&S Vanguard engine (2 cylinder) that doesn't start well. Replaced the battery and that worked for a few days, but now it is starting hard again. If I feather the gas pedal it will eventually start, but it can take several minutes of fussing to finally get it to kick in. I suspect it is electrical (alternator/generator?) because it usually starts up when jumped from a truck. But I don't know enough about the machine to be conclusive.

I also...

Toro Workman hard starting