My neighbour was throwing out some old junk and my 11 yr. old son was intrigued by an old sewing machine.

He was wondering what monetary value it may have. The writing on the machine is not very visible but we are fairly certain that it is a Singer as the Model no. is 31-20. There is also a serial no. L1184556.

Your help or input would be greatly appreciated.

If it is large it is most likely a 31-15 or a 31-20, if so, it's a good old machine. Just about anything that might be wrong with it is fixable as the parts are standard. I know people who have paid as little as $20 and as much as $200 for them, or gotten them for free, like your son did. The higher priced ones are tuned up and running well. You might list it on craigslist if you want to sell it.