The ornamental design for the fluoresecent lamp ballast, as shown and described.
FIG. 1 is a top, right, front perspective view;
FIG. 2 is a left elevation view;
FIG. 3 is a rear elevation view; and,
FIG 4 is a bottom, plan view.
The broken line showing in FIGS. 1, 2 and 3 is included for the purpose of
illustrating environmental structure only and forms no part of the claimed
design.