Apple II (original) power supply problem

[rogtha@delphi.com]

Here is the situation: I have a cooling fan attached to the left side vent
on my original 1978 Apple II. Sometimes, when I push the switch, the computer
will either emit a "click" or nothing at all, accompanied by a screen of
garbage. When I turn the computer off, wiggle the motherboard a bit, then
push the switch again, there's the normal "beep" and the disk drive is
initiated. Is this necessarily a power supply problem? I've tried different
fans and I get the same result. If it's a power supply malfunction, are
replacements for this model easy to acquire?
Please E-mail if you have any ideas.