Connect pin 11 to a slight negative supply, or connect a pull-down resistor from the output pin(s) to a negative supply.
The latter is probably the better option, as to bias the output stage into class A conduction. LM324 is a terrible opamp, with enough distortion to be noticeable even in control applications such as this. It needs all the help it can get (like by biasing the output).
Speaking of bad things being bad, and component paranoia -- mind that even the lowly 324 can and will be counterfeited by cheap suppliers. You might get salvaged parts, you might get dust, you might get something unexpectedly much better -- who knows? The same goes for every semiconductor; buy from authorized distributors if possible.
Tim