Image flickering requiring restart

My TiVo HD Series 3 (TCD652160) has been having occasional flickering of the image, usually with horizontal stripes, and always with audio cut-out. Been happening roughly weekly for the past few weeks. When it happens it will get worse over a period of 30 to 60 seconds. It resolves with a Restart, except once when the startup process ran for a couple of minutes then went to a black screen and I had to unplug/replug power.

Here's a short video: youtube.com/watch?v= qU3sgiULr_k

My TiVo has the original internal 160GB drive plus an external drive. I'm guessing that this is a power supply issue--I could easily replace it--but I'm worried about the drives being very old (2008).

Your thoughts?