Please help to diagnose a noise?

[notoriusb.e.n]

Well I'll try the Chain and Sprockets first, its going to want them anyway if they're still original after 10 years. Front sprocket seems to be hooking a bit. Could be combo of hooking front sprocket and stiff link in chain causing it to jump/slip about under power.

At least that's what I've got my hopes up for now. and its a simple cheap straightforward fix to try.