Well just to update, BG offered me a £12 refund, which I think is fair considering - I’d rather not return the whole light over it and not be able to get another, it would end up costing more.
It seems to ok without the screw, so I will accept.
Hence your copper FW3A will from this moment on be formally addressed as: Screwless Nick.
Lol!
Surprise surprise, no refund has been credited……. 
Escalated to Paypal now.
“We gave you refund. Please go post office and check.”
“Can you send pictures of not getting refund?”
“Maybe video, too?”
Typical Banggood :person_facepalming:
‘Banggood will do what we have promised to our customers. When you receive this email, we have already arranged a refund 11.63GBP to your payment account.’ :person_facepalming:
Maybe it’s like an arranged marriage and will happen in like 20yrs or so…
Nice! 
Agree with rooster, optics is centered by holes in pcb so pcb misalignment should not influence beam.
I would rather believe that beam problems are cased my misaligned leds, and this is caused by bad pcb designers (no room for extra solder).
Ok, update on this………
After a lengthy phone call with Paypal and a couple of really lovely American reps/manager I got paypal to pay me £10 back. NOTHING to do with BG who never refunded the £11.63.
They changed their stance after opening the Paypal dispute and wanted me to return it in original untouched (right, it’s copper and they know I have taken the screw out etc) condition.
The cost of Parcel force insured tracked to China was, wait for it , £47.50. I got the light for £41 The stupid thing is it NEVER came from China!!! it’s in a BG bag, and was dispatched from the Uk, now if it came from outside the UK it WOULD have had a customs declaration, which it didn’t.
They however would not let me return it to the UK address which is printed on my package, and insisted it had to go back to China!
Paypal saw what was going on and offered me £10 from them as a goodwill gesture, which I accepted because the guy and lady were so nice, we literally talked about the south coast of the UK for like 25 min!
Really nice call. So I get to keep the light, I got £10 back and I’m happy. NOT with BG though, who I STILL think were selling those ‘6’ special offer ones off as they were seconds.
2nd update - Banggood followed through and refunded my £11.63 today as promised - credit where credit is eventually due.