I just installed a 14-50 220volt receptacle (wired from the subpanel) for a car charger and noticed the neutral wire screw was so hard to screw in and out. The other three were fine, but this one took a LOT of effort to screw in. I had backed it out with less difficulty to accept the 6 gauge ground wire, but then could not screw it back in. I had not backed it out all the way so there was no chance of cross-threading. I eventually used a driver drill and the bit (el cheapo) broke off---it was that tight! I used another bit and barely got it to bite hard. The screw had typical phillips/flat head combo.

What am I missing?? At the time of my frustration I assumed I got a lemon but maybe I did something wrong???

 

... not completely sure if it's the same, but a recent problem with an electric dryer 240 volt receptacle required wiggling the screw to get it to install. After the wiggling ... no other word for it ... there were no further problems. The screw had been completely removed, but a few wiggles caused it to get started with no effort at all.
... something to try out.

 

The screw was cross threaded or similar...
It happens..

 

Yeah. Stuff happens. Oh well. It's in at least.