I put a piece of farm machinery on both Craigslist and Facebook marketplace, over a month ago.  Roughly a week ago a farmer called, we texted and made arrangements for him to get it.  He showed up and handed me the cash.

I also posted a piece of shop machinery a couple weeks ago and within 2 days I got a response.  Made arrangements with the guy, he showed up with friends and handed me cash.  This time I had asked if he could pay cash and he responded no problem. 

I place multiple pictures of the items I wanted to sell, had a reasonable price, and an explanation of why I was selling them.

Maybe some of those things made a difference.  I did get one inquiry from a person that looking at their profile quickly convinced me not to bother.

I hope if you utilize one of these free services you have the kind of success I did.