Were both bulbs originally working? bulbs went in probably same time...so both could've blown. Generally u can shake and it will rattle if blown,. always could buy 1 if not the problem, u will have a spare. DON"T touch the bulb oil from your skin will cause it to blow. Also, if u are new a 750 is probably too big to start on. I rode a 500 for 4 years b4 getting a 750.If u are abdamant, then u will want to take it easy on the 750.