Good advice so far. I am not sure why you want to reverse the "normal" direction but I am sure you have a good reason. Being an electrician (retired now), most motors sold these days are not reversible. You will indeed have to have it checked out by a person knowledgeable in this area. If you take the motor off and take it to a motor shop, not a place that just sells motors but one that works on them, they can look at it and tell you if it is even possible to do it with that motor. If they say yes, they might sell you the needed parts and even install the parts for a nominal charge. or give you a wiring diagram you can follow. It wont be cheap for the reversible drum switch if that is what it takes, but taking it to them is a lot cheaper than them coming to you! Not sure what area you are from, but an electrician around here in West Texas is about $125.00 an hour with two hour minimum. Too pricey for me and a plumber is even higher!
Good luck! and remember...
ONE GOOD TURN DESERVES ANOTHER!