Laptop no longer powered by AC adaptor

Hello, friends of /comp/.

Today I noticed that my laptop wasn't being powered by the mains adaptor. It's a Thinkpad T40.

The adaptor transformer used to get really hot, and I've had it on for a week or so now, and it no longer works. If I listen really carefully to the transformer, there's a really quiet buzzing on one side of it (normal I presume) and a slight squealing on the other (not sure if that's right).

Basically, I assume that either the transformer or the AC connection on the laptop is broken. Could you hazard a guess at what could be the problem? Perhaps the power connections on Thinkpads are especially fragile, or maybe these transformers are prone to burning out... I have no idea, but I'm hoping you guys will. I'm hoping it's just the transformer, as that's a much cheaper fix than the part of the laptop.

Thanks in advance for any advice.

Another thing:

Upon plugging the adapter into the laptop, the battery light flashes for a split second. Even with careful wiggling, I can't find the spot where it connects, leading me to believe that the connection is fine, and the flash is caused by the tiny amount of power in the transformer.