Originally Posted by garage sale GT

I don't know. There's no substitute for correct chain length and adequate derailleur tension. You can get a new Falcon rear derailleur from Amazon which is a lot like the unit on that Huffy. Its spring may be tired due to rust pits or fatigue cracks, if you have a problem with the chain coming off. I've had lots of bikes with no chainguards, good ones and cheap ones, and no problem with chain derailment if the chain tension was good.