I am working on a 52inch Gateway Great Dane walk behind. The engine blew and I am working on rebuilding it. My question is this, How in the hell do you disengage the hydrostatic drive? Someone told me to turn the little levers on the inside of each drive unit. I have tried to turn them and they don't move. If this is the way to disengage the drive which way do they need to turn. Thanks in advance for your help, Andrew.