MK125 faults

I have trouble with MK125 mini kits in that one worked for about a year and has stopped now but a new one only worked for a few minutes befoe stopping. I suspect the IC to be faulty. Any ideas. Thanks for any help.

This is a classic circuit, which has proved its reliability.
Check power supply circuit (regulator). If necessary, replace. If supply is ok, replace LM324 (very cheap and common).