It should take a week for the caps and transformer to charge down without a bleeding resistor in the transformer. It should take about 10 minutes for the caps and transformer to charge down fully if it has a bleeder resistor in the transformer.

The head of the snake is at the metal clip inside the suction cup on the CRT, as this is where the 1-12 KV is at. Then there is the circuit around the transformer on the top of the circuit board which has a lower voltage but at a high amperage. When dealing with the Analog board, only hold it by the edges, and never touch the traces unless you are working on it and only after you discharge it.

Many early Macs like your 128K have transformers without a safety bleeder resistor. To discharge them, read: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html#DischargeCRT