NAD 2600 and thumping noise


Okay, I just got a nice deal on an NAD 2600. However, when I turn it on and off there is a fairly loud THUMP. Even if the volume is turned down and the inputs are removed, it is still there. I know this isn't much to go on, but any ideas? Is this a matter of cleaning this baby up? Or have I bought a dying beast? Or something in between?

Many thanks! Aaron
aewhistory
Hi bojack, thanks for the reply and sorry for my slow response. I hate to ask, but is this an expensive fix? Also, is it something I could put off? Finally, if I am going to do that, would it be worth having other work done to the amp?

Oh, a stupid question: what exactly are the relays? (hides head in shame)
Actually, does anyone ever mod NADs the way Adcoms and other get the mod treatment?