I have always used the lightest bobbin I could get away with, using the ESP white bobbins with Steve Neville buzzers, however recently I’ve noticed that on several runs, I’ve had the bobbin jam in the roller on the buzzer which silences the alarm as the roller couldn’t spin, so I swapped them out for a set of new direction mini swingers, with an adjustable weight, they do the job nicely, as the arm stops the bobbin reaching the roller