it definately sounds like a cold oil problem. if it cures after a couple of runs this would indicate it. the viscosity of the oil when cold makes it thicker and therefore slightly harder for the up/dn valves to close over ergo the lift runs on a little. i would recommend you tell the customer that you try it and if it doesnt work then you will bear the cost, but if it does then they should apply these to both lifts at their cost. also remember it varies from block to block which may be the reason why its different on the other lift and wouldnt be surprised if it has a block heater in it. you should always have a block and oil heater as a base level for all hydros and and oil cooler for high traffic/temp areas.