Ingersoll Rand sd45d wont go forward or reverse after 40 min of use

Got an Ingersoll Rand sd45D, after about 45 min of use after it gets up in temp it wont go forward or reverse. Happens only if I apply the park brake. If I dont apply the park brake it will run the whole time, if I have to get out of the machine and apply park brake I cant get it to roll again, Have to wait 20 or so minutes. I can hear the brake being released so its not sticking. If I hold down the botton next to the park Brake the machine starts to move but feels like only the front roller is moving. Thanks for your help guys -Alex