As others have noted, we need more information - which model lathe, and more importantly, is it a variable speed lathe with a DC motor.
A fundamental issue is that a variable speed lathe with a DC motor varies the speed by varying the voltage applied to the motor. But, reducing the voltage also cause the torque produced by the motor to reduce. Sorry - that's basic electrical physics and applies to all variable speed lathes with DC motors. And what it means is that variable speed lathes with DC motors are notorious for wanting to stall when operated at low speeds. This problem is most obvious with large diameter turnings and when drilling.
Variable speed operation is a convenience, but the price that must be paid for that convenience is reduced torque at low speeds.