> Thanks Dieter, So both LM324 amplifiers are identical

Yes

>Is it worth replacing the socket the chip plugs into

No

> I guess I order one of the top two chips below:
>
> http://www.rapidonline.com/Electronic-Components/Integrated-Circui
> ts/Operational-Amplifiers/Operational-amplifiers/67379/kw/82-0228
> source=googleps&utm_source=googleps

Yes, but pay attention not to order the smd types.

Best wishes
Dieter Doepfer