Macbook issues with wall charger

Hi,

I have had a unibody macbook (not macbook pro) for 2.5 years and yesterday two issues suddenly came up when the charger is plugged in.

One is that the track pad will only work properly when I'm touching the case at the same time (resting my wrist on the body), this isn't really inconvenient it's strange that I never needed to do this before. Otherwise it becomes unresponsive and erratic.

Two is that when I have my external speakers plugged in as the macbook is charging I will get a loud buzzing, I've tested the speakers on other laptops and it works fine. The problem is not apparent when the macbook is not charging.

Is the charger dying or is there something I can do without having to buy a replacement?

Note: No 3 year warranty

Thanks