I just looked at the photo of Bintels 20mm and it looks the same as yours here Micheal , with the nice alloy illuminator , so if yours RG has a cheep plastic one it is not the same as advertised , grossly inferier I would think reading your reports .
I have delt with Bintel alot over the years ( as most of us have ) and even with the stripped thread I almost %100 guarentee they will replace it , they are very good like that , and another thing I am sure they would like to know of this , wouldn't you ? ( looks like a lemon slipped thru )
Have a great christmas .
Brian.