Having been busy elsewhere I finally picked up a "Headlamp Restore" kit from the local Harbor Freight Tools for the grand sum of $8.99 (with $1 discount leaflet).
Two small wet/dry scourer pads plus a larger foam backed polisher and some fine polishing "goop" - it certainly took a lot of the bloom of the lens but the "nipple" in the middle of the lens caught the pads and soon destroyed them...
That being said, they looked better, so checking them out a few days later I note that both seemed to have water INSIDE
a small hole bored at bottom center produced a neat little cascade of water
So, now I know the units are not sealed I'm determined to simply replace them - Amazon have a pair for $42 and change - for some odd reason the three retailers are all based in California.
More on this when they arrive and no doubt will give me more grief