I was charged £40 for replacing my compressor which I was more than happy with. I dismantled my old one as I was interested to see how it worked. Apart from the air receiver, which is basically a cylinder with a fine filter, it has a piston and con rod with a plastic compression ring. Fairly basic really. So there are areas that wear, which although not serious, they can cause noise, as I discovered, so it's not always the rubber bushes causing the problem. The rumble from the compressor was the only negotiating point when I bought mine, which could have put me off buying it, but as I now realise, it's not a big problem.