Assuming it is B-E junction failure going ohmic. It will be low current
transistors showing the effect first, it may be inside other higher current
ones but not manifesting as a problem yet. For fault finding I suppose one
route is to check TO92 first and of those the lightest current ones first eg
highest base resistor values first , if no other knowledge.
A trouble with these sort of biasing circuit areas is an almost total lack
of grounded nodes so everything is floating up or down together.