Picked up an old Hygain bilateral linear amplifier recently. It is in pretty
good condition considering it's age. The problem is that there is a 25v
100ufd cap that has a broken lead at one end so I am not sure where it broke
off from and no tell tale wire nub form any nearby component that I can
find. One end is attached to the 12Vdc negative power lug on the inside of
the amp. It looks like it may have broken off another ground lug or the
positive 12Vdc lug but I am only guessing due to the broken leads' length. I
have searchd but cannot find a schematic or online manual so far. Thought
someone here might have one and could let me know what the proper connection
is. Thanks for any assistance.

The 25V 100ufd capacitor is should be connected to the positive and negative power input terminals. Hope this helps!