have you tried tightening the heat-sink screw and touching up the three
solder joints? A lot of these transistors lift their legs off the Pc
board after a few hundred heat/cool cycles, or break their pads off the
Pc board.

Otherwise if it is a flaky transistor, it shouldnt be too critical,
it's just a 300V NPN 200Ma transistor. There's three of these on most
color TV CRT socket boards, as video drivers.

Regards,

George

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