Is My Air Pump A Gonner?

[jackrmee]

I found an old air pump in the drawer. 
It works, but the further down the tank I put the airstone, the slower the bubbles come out, until they finally stop at the bottom.
It's not pushing the air out strongly enough. Is it knackered, so to speak?

 

[Fishmanic]

if you want to confirm that its worn out, open up the pump (screws on the bottom) and inspect the bellows.  If you see any splits in the rubber bellows, unless you can buy new bellows, then shop for another air pump.  But before doing this, be sure the airline is tightly attached and doesnt leak around the connections at the the airstone or ornament.