T20 power supply problem

Archived from groups: comp.sys.laptops (More info?)

I have an IBM T20, and a few days ago I plugged it in and the screen
brightness pulsated as if the laptop were constantly switching between
battery & PSU, and it in fact ran the battery down. When it was
switched off but plugged in, the laptop made a clicking noise and the
orange led flashed. When the PSU was unplugged from the wall, the
clicking continued for a few seconds.
I took it to a Radio Shack, and we plugged it in to a suitable PSU
there, and the laptop worked fine, and then continued to work ok on
it's own PSU for 2 days.
Now it's doing the same thing again. It ran for about an hour with the
battery indicating 1%, but finally died. Now it won't power it at all,
even when plugged in.

Does anyone have any experience with this issue, specifically if it's a
PSU or a laptop problem? (note: the Radio Shack was in another state -
I've yet to find a replacement PSU in my city)

Thanks.