Hmm, interesting. Does the mower actually start, or just slow to start?
Honda mowers are usually bullet proof. The need an oil change every other season, lube friction points and clean the air filter and check the spark plug gap each year. Even the drive belt is good for 10+ years!
I had problems with mine getting it to start last year and eventually traced the problem to a faulty ignition coil. Local Honda dealer wanted £40+ (half hour) just to look at it. I didn't buy the genuine part given it was fairly expensive. Think I possibly sourced it online.