Starting issues

Hi,
I have just inherited my father’s house and land and in his garage is his Grizzly 350. I have used this a number of times in the past when I have been helping him. However, on my last few visits it wouldn’t start on the starter, but is fine using the manual pull starter. When I press the starter button there is a click from below the seat.
I know plenty about restoring old cars, but the Grizzly is something completely new to me.
Any help will be gratefully received. Also any general advice on looking after it, servicing, etc.
Nick