I have had various models of 47 over the years, Currently have a G 5 which starts a dream. 5 or 6 primes, wait for a minute and I usually start with mags on. This works for me.
Only trouble over the years is if Battery is getting a bit tired, and a new battery sorted that !
Most of the machines I have had, had fairly sloppy throttle controls, so when you think you have throttle at quarter of a turn for starting, it may not be far enough.