Do like I did. Bypass the pump and ride it for awhile to be sure it's the pump. Then take it to them and explain to them that by disabiling and bypassing the pump the bike runs good. It's an intermittent problem, it may be doing fine, but you want it replaced because the bike is not reliable with it hooked up. The warranty is suppose to cover it so it's not coming out of their pocket. As a matter of fact they make money doing warranty work! If they still won't do it, go somewhere else. If no one else wants to change it out, go over their heads and call the customer service number. It's a known fact that the pumps go bad slowly or all at once. They'll probably want to keep the bike a few days and check it out, but talk it out with the service manger and try to get him to see your point of view and if you are like me, the bike is ridden daily so it doesn't need to be kept in a service shop more than it takes to replace the pump.