The hydraulic pump is attached to the crankshaft with a splined coupler. Remove the 4 bolts from the coupler to crankshaft. There is a notch in the engine (harp) mount the bolts will only come out when lined up with that notch. Once all 4 bolts are out slide the coupler towards the pump, it will leave you room to get the belt on. Reverse order for assembly. I'd spray the coupler with penetrating oil they tend to rust up.