I have a new Exmark Quest 48"/22hp B&S ELS (14 hours) that is running forward slower than it should. The brochures and salesmen told me it would run 7 mph. The best I could get on flat ground with NO blades engaged was 5.7 mph (per my GPS) and while cutting 8-10" grass it would not pass 5.2 mph again on flat ground. Is there something wrong/adjustment required or am I just another victim of deceptive advertising? The hyrdro filter is new since the mower is new but I did need to add about 3 ounces in the reservoir before I did my test since it was low. I tried to adust the tracking per the manual, but it would not adjust. Should I try the dealer; hopefully under the warranty? Thanks.