How do you check if your modem has gone bad?

I am wondering this because it feels like webpages are loading really slow and my ping times to game servers have increased.

To the speedtest.net chicago server i was getting 12ms ping time now its at 31-50ms ping time.

In counter strike source my ping to chicago servers is around 80ms when it never has gone above 35ms for a chicago counter strike source server in the 1.5 years that i have played css.

Any help plz.

Comcast is my internet provider and i have the 8 meg version.

hmmm.

try this
Run -> Cmd
in Comprmt type in tracert then your IP address. you should be able to monitor every connection it go through. you should be able to see where it is dodge, then ring comcast and get em to sort it.

Try a different PCI ethernet card to rule out the ethernet connection on your board. Check the ethernet cable for cracks, etc.
Do you use a router?
Try bypassing the router.

try resetting it as well, it might be in fubar mode.

i've seen results with powering modems off for 24 hours, provider will dump your address from existing tables, and rebuild when you get back online - normally with a 'least cost route' = 'fastest path' to your destinations.