Well, the wealth of info in here saved me the cost of new headlights-add me to the list of satisfied headlight screwers.

I used what seemed to be the recommended length sheet metal screws but I find the the right side pointing up to the street signs at night and reflecting them directly. Can the crew be backed out a turn or 2 to level it out or does it need to be snugged tight to the lens? I'm loathe to remove it and replace with a shorter one as I think it'd compromise the screwhole 'tightness' as happens to most holes with 'too many in & outs.'

signed,

screwed tight in FL

 

I had the same issue , when I bought my s type , the left hand head light was facing down .
I done the screw fix , to the letter and it was too high I removed the screw several times and ground the tiniest bit of the tip of the screw till it was perfect , I'm sure it was over a mm can't remember , but within 6 monthes of doing that the right hand headlight dropped aswell . So rather than drill another lense , I purchest the headlight adjuster upgrade kit from eBay . These are reinforced resin adjusters mutch stronger than the factory ones !
I pulled the front off the car split the lenses off and fitted the adjusters and sealed the screw hole and haven't looked back , no problems since .
It seems the genral consensus is to replace the headlight but realy you can repair them .

 

Commendable job, lots of work. And are the new units improved to the same friable plastic as the originals?

 

Yes . I have one original lamp and one 2 year old head light and the new one broke first .
Both were the brittle white plastic .