Never seen an A1200 doing this before!

[save2600]

(power LED is generally supposed to be dim for a second or two on powerup before going bright on a 1200, correct?)

That's an Amiga attribute AFAIK. Any Amiga I've ever used seem to exhibit that upon startup anyway. That would include all models sans a 3000T, 4000T, CDTV, A1500 or a 500+. lol

Maybe someone performed a hardware hack bypassing the audio filter? Have you opened it up yet to clean out the dead spiders and cockroaches? lol

[save2600]

Yea its been thoroughly cleaned, seemed fine on the inside.  Very very strange...

So you looked REAL close at the circuit board? By the LED power connector from the CPU board? How about up on the keyboard where the wires lead to for any broken or cut traces?  

Does the light instantly come on after the machine has been on for a while and you perform a warm boot? If it does, than yeah - sounds like a bad cap.