I recently purchased a screw bezel case from here and I had terrible trouble refitting the back.

Not complaining as I had warning of this in the listing.

It was locking almost a full turn from fully down.

Spent a long time screwing in both directions in an attempt to free it up and to get it to go fully down but it felt and sounded like something gritty causing it to bind.

I tried cleaning the threads and rubbing peg wood in them but again no joy.

In desperation I sprayed the threads with silicon oil but it still felt gritty and wouldn't go down.

As a last resort I applied a minute amount of wheel bearing grease ( I know but it's all I had ) with peg wood to the threads and it was like a magic spell.

The back went all the way down as smooth as silk.

Have others here used this method to ease a stiff case? I've not seen it suggested.

Also is it wise to leave a smear of great on the threads when fitting a movement in or should it be cleaned off using an ultrasonic cleaner and left dry again.

I would welcome your observations and suggestions.

Thanks Mike

Mike,I have had the same problem(as I am sure everyone has)after chasing the threads with a very
small screwdriver and cleaning with toothpaste
I generally apply a small amount of chapstick
to a couple of places.Then work back and forth.Seems to help quite a bit.I have never used
bearing grease but a small amount I don't believe
will hurt anything.
Roger

Grease? Interestingly I read a post that after a COA the watchmaker did a thin grease smear on the inside back cover. Called it a grease magnet.